I keep clicking "Install" but it seems to fail and never actually install. Any ideas?
Windows 10, using the Itch client, fwiw.
ACTUALLY, if he is using the Itch app then this can be caused by another issue.
Avast antivirus WILL prevent itch from installing anything, including itself. Unless you make exeptions for the Itch.exe in avast. (This doesn't mean Avast is bad or malware, it's just doing it's job and preventing things that arent explicitly permited from changing files.)