I have a lot of GoG games, and only one so far that won't run on my PC. I have had a couple of problems with their Linux/Wine setups.
If a game doesn't work for you, and support can't get it working, GoG will give you a refund.
You should be able to download via your browser, if you don't want to use Galaxy. Just log into your account, and go to your Library. You should get a display of your games, and selecting one brings you to a screen with download options. (Linux users have to do it this way.)
Today is the last day before Tomorrow happens. Procrastinators take note.