You need this! (Source Control with Git & BitBucket)
Source Control is a must-have for all developers. It gives you version control, online backup, and collaboration features - all for free!
Why does this tutorial not cover the in-built SCM features of GameMaker Studio 2?
Because it's not perfect and many people have had problems with it, making Git the better choice.
Download Git: https://git-scm.com/downloads
Credits for icons used:
https://icons8.com/
https://thenounproject.com