What is this building? Garage?
When was it built?
Is this just temporary or permanent housing for birds?
I think your cheapest solution would be to lay a heavy mill plastic down, then lay sheeting (osb) down, if this is temporary. Pitch the osb when you move the birds out.
Don't seal it...
I can agree with you, sort of... And my fault for not going further in depth. Water will seep up from under, same as it will soak in.
Which could be construed as condensation because it usually happens in the spring when temps start rising.
A sealer will help stop that, and not allow the smells...
A concrete sealer would be your best choice.
I have a 24x24 pole barn with concrete floor. This is where all my coops are for the moment.
I have ducks also and as they sleep on the floor I built a subfloor for their coop. I laid down plastic, 2" foam, then built the sub floor on top... Thick...
Concrete sweating is normal. Warm air over cold concrete causes sweating.
Here's some helpful info and suggestions to stop it.
https://ghostshield.com/articles/how-to-stop-concrete-sweating#:~:text=Concrete sweating is often times,the concrete floor to sweat.