[Github Desktop] Failed to publish branch

I tried to create a github repo with an Unreal Engine project.
I followed exactly the steps described here :

However when I try to publish my repo on Github, it takes forever and ends with “Failed to publish this branch”.

Notice that I created a project from a 2D scroller sample, so there was already some content (600MO).

Maybe that’s why it could not publish the project.

But there must be a way that I can publish my repo.