Repository from GIT not recognizing Java/SDK

I have the following problem:

I'm currently working on a project with a friend, which we decided to put up in a git repository. When i clone my own repository, i select an SDK and everything works fine. When I clone the repository from my friend, it also asks for an SDK but when declared, it doesn't seem to work as the IDEA doesn't recognise the java files (which also means i cannot compile the code).

Everything used to be fine, but I had to delete my local copy last week and had to clone it again, but now it just won't work anymore.

This is my own repository, where everything works fine.

The repository of my friend however looks like this

I have full rights in the repository, means I can update my files and push&commit and it won't throw errors. Does anyone have suggestions to solve this problem? I'm fairly new to programming so bare with my foolishness.