Count Dooku ordered the clone army as he impersonated Jedi Master Sifo-Dyas in order to get the clones commissioned.
In this scene, he wasn't surprised when the Army of the Republic arrives:
He was calm and relaxed when the clones landed. Did he really know that the clones were coming, considering that he had an allegiance with the Galactic Republic (secretly with Darth Sidious) and the Confederacy of Independent Systems?
The dialogue at the end of the film between Dooku (Tyranus) and Palpatine (Sidious) makes it explicit that their plans had been fulfilled:
DARTH TYRANUS: The Force is with us, my Master.
DARTH SIDIOUS: Welcome home, Lord Tyranus. You have done well.
DARTH TYRANUS: I bring you good news, my Lord. The war has begun.
DARTH SIDIOUS: Excellent. Everything is going as planned.
The whole plot was carefully orchestrated to lead up to that point. Consider:
Seriously, there was no sensible reason for the assassination attempt. All it did was draw the Jedi's attention.
When his accomplice was about to talk, he shot her with a Kaminoan sabredart. He could have used a blaster bolt - a common, near-universal weapon, which leaves no physical evidence. Instead he used a weapon apparently unique to Kamino, which left behind physical evidence the Jedi could examine and trace back to Kamino.
He gives obviously evasive answers, he leaves his armour where Obi-wan can see it, despite having ample warning to hide it - indeed, if you watch the scene, you see that he comes out of the room the armour was in, leaving the door open behind him. He stands between Obi-wan and the armour, then he moves aside, making sure Obi-wan can see the armour, and draws attention to it by having Boba go over and close the door.
Again, why? Of all the places he could go after a fight with a Jedi, he goes running straight to his real employer?
So what we have is Dooku's chief henchman first leading the Jedi to Kamino, to discover the clone army that has been bred specifically for the Republic's use, then leading the same Jedi to Geonosis. Either Jango is seriously incompetent, or it was deliberate.
Dooku stalls, 'interrogating' Obi-Wan instead of just killing him right away. He waits for Obi-Wan's rescue to arrive, and when they aren't what he'd hoped for - just Anakin and Padme - he sets up an overly-elaborate and time-consuming execution for them.
After the battle with the Jedi, Dooku continues to stall. He offers the Jedi a chance to surrender. He takes his time ordering their death. He does everything he can. FINALLY, Yoda turns up with the clones, all hell breaks loose, and Dooku quickly gives up all hope and tells the separatist leaders to evacuate.
After the battle, Tyranus returns to Coruscant to meet with his master. The dialogue goes thus:
It is very clear from the dialogue that what happened was EXACTLY what they had planned.
The whole film consisted of Sidious and Tyranus leading the Jedi around by the nose, carefully laying out the pieces and waiting for them to bite.
The film's novelisations and screenplay (which includes both external and internal dialogue from Dooku) both clearly indicate that Dooku had absolutely no idea that the Jedi were coming. He was looking forward to a nice execution and was surprised by both the arrival of the Jedi strike force and then doubly surprised by the arrival of the Army of the Republic.
His surprise at the arrival of the Jedi
Mace Windu stood next to Jango, his lightsaber glowing a clear purple. The noise of the crowd must have covered the sound when he ignited it, Dooku thought. He hid his surprise with an elegant nod of welcome. “Master Windu, how pleasant of you to join us. You’re just in time for the moment of truth.” He gestured at the arena. “I think these two new boys of yours could use a little more training.”
and
[COUNT DOOKU masks his surprise elegantly as he surveys the arena and sees JEDI KNIGHTS standing at every entrance and exit.]
His surprise at the arrival of the Army
“The Jedi have amassed a huge army!” Nute Gunray cried.
“Where did they get them?” Dooku asked, sounding perplexed. “That doesn’t seem possible. How did the Jedi come up with an army so quickly?”
“We must send all available droids into battle,” Nute Gunray demanded.
But Dooku, staring at the myriad of scenes, at the many battles and explosions all about the region, was shaking his head before the Neimoidian could begin to argue his reasoning. “There are too many,” the Count said, his voice full of resignation. “They will soon have us surrounded.”
Obviously he knew of the existence of the clone army in general terms (having funded its creation) but the fact that he was on the planet all, the fact that he had to flee to prevent his capture and the fact that the entire Separatist leadership were nearly killed would strongly suggest that he had no idea that the Jedi would be able to access this army, nor that they could bring it to the planet in sufficient numbers to face down the droid armies of the Geonosians.
Tyranus, without question, knew of the Army's existence. He also did not appear at all surprised when they arrived.
Jango Fett: "I was recruited by a man called Tyranus on one of the moons of Bogden." That was before Sidious was even Lord of the Sith, he was still apprenticed to Plagueis. I’m fairly certain Darth Tyranus/Count Dooku was involved in Sidious’s plot to betray and murder Plagueis.
The Clone Army was commissioned by Jedi Master Sifo-Dyas. Sifo-Dyas was very likely manipulated through psychological and Force manipulation into this by Darth Plagueis and his then apprentice, Darth Sidious. I used to have a theory that Sifo-Dyas was an alter-ego of Plagueis or Sidious. The new information on Sifo-Dyas from Clone Wars kind of throws a kink in that, but I think there still might be something there. https://starwars.fandom.com/wiki/Sifo-Dyas/Legends
More evidence to support Sidious and Tyranus being behind Sifo-Dyas ordering the army, from the original script for Episode I: NOTE: THIS IS NOT THE FINAL SCRIPT IN THE MOVIE. I HAVE PUT CERTAIN KEY DIFFERENCES AND CUT LINES IN ITALICS.
OBI-WAN: Then you must know Master Sido-Dyas?
JANGO: Master who?
OBI-WAN: Sido-Dyas. Isn’t he the Jedi who hired you for this job?
JANGO: Never heard of him. I was recruited by a man called Darth Tyranus on one of the moons of Bogden.
OBI-WAN: No? I thought...
TAUN WE: Sido-Dyas told us to expect him. And he showed up just when your Jedi Master said he would. We have kept the Jedi’s involvement a secret until your arrival, just as your Master requested.
OBI-WAN: Curious...
https://www.imsdb.com/scripts/Star-Wars-Attack-of-the-Clones.html
