The download for Risen says 1.7 GB, but when I start the download it says 1.6 GB. I download the 1.6 GB setup file at 100%, but it doesn't work. On Google Chrome, the setup file is red and it says your computer is doing too many things right now, try again later. On Firefox, it doesn't work either after a 100% download. This is the only game I have on Gog that I can't even install.

Have you tried using the GOG Downloader (assuming you don't want to use GOG Galaxy at all)?

Thanks. I used GOG downloader and it worked.