Here is what I got from the dragonruby discord server:
so the simplest way, end to end:
Keep a copy of the DragonRuby zip
To set up a project, unzip a copy of it and name it something helpful
Inside this new folder will be a dragonruby.exe, and within \mygame\app\ will be a main.rb edit main.rb and run dragonruby.exe
You have to unzip the DragonRuby installation Zip file into a new place for each project you want to have.
Anyway, this is the easy method. For custom files and setups, I don't know how to do it.