I can't open it?
Can you be more specific ? You can't open the main zip file ?
It says an error when I try to launch
Oh, I just realized that there was no executable and not a "game". I still don't know what the starting point is so I can't really initiate the game. I do have 7z/file compressor.
If you go to your "owned games" page, and right click on the game, one of the options is to view the folder in the file browser. Click on that option. Everything in the folder it takes you to is part of the game. From there, start opening up folders, within the one you started at, and see what happens!