Hello,
This is my first time commenting so sorry if I’m bad at explaining things. I had this same problem with downloading where it got stuck at 100% and never fully downloaded. Tried all the solutions I could find but none of them seemed to work. After many trials and errors I found one solution which worked and it includes using VPN. I am using “Windscribe” VPN set to Germany (it’s the closest best performing connection) and after restarting Quixel Bridge and downloading assets again it all worked perfectly fine.
Hope this comment helps others with this issue.