Side note:
I would recommend against using Atom, especially since you’re just starting out and (presumably) not used to any one editor at this point.
Atom still, even though the issue was reported years ago, has a nasty habit of deleting code. If you decide to use Atom, Git/version control is absolutely imperative.
Also, in my opinion, a “hackable text editor” is no substitute for a proper IDE. VScode is a similar free and lightweight text editor, yet it features the same IntelliSense language server that powers Microsoft’s enterprise IDEs (Visual Studio). Atom’s language server simply does not compare.
I’m sure some will disagree; these are just my two cents. (And yes, it’s quite easy to integrate PROS with other IDEs.)