Hi Jonas,
I'd like to suggest www.replicastudios.com be added to the list of free sound libraries that can be used for this game jam!
Replica make AI voices for games and movies, and we have a free trial period that should be sufficient for teams participating.
You can listen to demo samples here before you sign up for an account : www.replicastudios.com/unreal
All the best!
- Shreyas @ Replica Studios.