amrit9037: Yes. it happened with someone else too earlier.
Try these.
Turn off Avast.
Try Inno Extract to extract Setup files.
Turn on avast and scan extracted files and note down the name of file(s) it detect as threat.
Upload all files to
Virus Total.
If other antivirus says it's a threat then you can assassinate Agent 47 else add it to Avast exception list.
Mostly GOG games are just false positive.
Had the same issue and reported it to Avast on Monday. In my case though, Avast just considered the "hitman.exe" file to be "FileRepMalware" instead of deleting all of my game files, so I could run the "setup.exe" file without fail, but not the main game.