How can my friend access my unreal engine game

I added my friend to my unreal engine project. how can he work on the game now? Because he has no access to the game anywhere

If you provided a link to the actual repository it would be easier to answer.

The issue might be due to different reasons, from files being ignored by the repository which he needs for running the project but require building the whole project or running some dependencies script. It’s impossible to answer without being able to look at the repository contents.