Have tried multiple times to install, but it stops at 2%...

Definitely a question for gog support.

You’ll want to try the ideas of redownloading and ensuring you have all the files if not using galaxy.

If using galaxy, not sure. I used to have to set a concurrent downloads setting to 1, but I’m not sure if I do anymore. I haven’t tweaked its settings in many years.

Best of luck (several months after the fact).