I am a complete newbie to this stuff and struggled for several days trying to set up the SourceTree/GitHub/Unreal connectivity. The more I studied the more I realized that I was lost and not getting it right. I made several false tries and some didn’t want to move so many files.
Finally I went to YouTube and searched for Unreal/GitHub tutorials and found one that worked. Basically in the new Unreal engine there is a source link at the top that you can click on to activate a GitHub repository from the game itself. Once you have that repository you can connect to SourceTree and it will track changes.
I’m not dumb but I struggled for over four days with this issue so I thought others might be struggling as well. Hope this helps! I love this course and am having lots of fun and lots of challenges.