I am not a HVAC contractor, but attic venting, insulations types and vapor management are common enough contractor issues.
I am not sure how the spray foam is being installed in your house. Is your attic being converted from an unconditioned, vented space to a "conditioned," vented space?
If you are moving the house's heating/cooling envelope you may in effect be moving a piece of machinery that used to be "outside" to the "inside" of your home. You definitely do not want the condenser "exhausting" hot wet air inside a closed attic (and ideally the compressor which generates heat would be outside as well).
For gospel on attic venting:
I hope this helps,