Hi Space, I'm hoping you can give me a little more information.
groupthink requires port forwarding to work online, did you do that?
If you successfully got port forwarding set up, could you both connect to the server? You'll know that your friend and you are both connected to the server since you'll both be seeing the same map after a connection is completed.
All controls for network play use the up/down/left/right arrows for movement and space for actions so if one of you is trying to use WASD or any other customized controls then you won't be doing anything in the game.
You're the first person to mention problems with groupthink online so thanks for the feedback and I hope I can help you. Thanks for your interest in my game!