Orders came flooding in for hemp oil, seeds, lotions, shampoos and conditioners.
I'm trying to translate a sentence very similar to this one, and it seems to me that the verb is 'to come in', and 'flooding' is an adverb. It that correct?
Here 'come' is a verb and 'flood in' is a verb.
'Flood in' - To move quickly into some place or thing in large numbers Source
Here it is using the gerund form 'flooding in'.
'come' - Move or travel towards the speaker. Source
So the orders are arriving at the speaker in large, sudden and/or unexpected numbers
Some more examples and analysis can be found here