You may not have the appropriate permissions to access the item. I'm admin in windows, only one account, I can run anything from C# net in visual studio, git, unreal engine, NO issues.
Any ideas?
Also, guys, try Vroid Studio - it's also free....

Hello! Do you have any screenshots of that? We double-checked, and it seems that everything is fine both when installing using itch.io app or running it via extracted ZIP download. If you're using the itch.io app, you can try to reinstall the build using the gear icon available in the bottom right of the app info page.

EDIT: We are aware of VRoid since a long time now :) We have a different direction by going through 2D path and try to mimic artworks from 2D artists as much as possible. We continuosly evaluate other apps and see what can be added to give ours more capabilities.