How to collaborate on Unity 3D VR Project for 4 People?

Hi there,

I am looking at creating a VR game as part of a university project along with 3 other people.
We have been given free rein to design any sort of game except it has to use Unity 3D and Gitlab.

However, we have not been able to find suitable way to work on it.
Currently we have it setup so 3 of us can access the project through Unity DevOps but cannot get a 4th member without paying for the premium. So far this method has been a bit clunky and a lot of issues with setup.

I’ve managed to use Github and Github desktop in the past successfully but I haven’t been able to figure out how to link it with Unity.

Do you guys know anyother way we can collaborate on a project together and roughly how we would go about it?

Thanks!