GOG Galaxy issue inguess... Cant say why its stuck. Something prevent saving files on Internal Drive or something prevent from downloading.
Fist is 100% settings/security settings on your PC. Downloading issues looks like sometimes happening on fontent providers servers side.
Try check up BOTH Steam and GOG articles on PCGamingWiki, and then general Troubleshooting_guide on same wiki.
Galaxy use differ folders to download and to install games depand on settings. In any setups better if everything gaming related is outside of system logical drive. D/Games/GOG-Galaxy/
and games in X/Games/Game-name-9/.
Still to install launch galaxy.exe in ADMIN Mode.
