If I may ask, are you European based? I've noticed an issues where if you attempt download some games from within Europe you would get a corrupted version but if you were to instead download from the US you could install fine, which I personally verified through a VPN as well as some users still being able to install the game that's supposedly corrupted. I reckon the EU server Itch are using is deteriorating and corrupting it's instances of the programs, seems plausible since this issue has really started to ramp up recently within Europe but outside is unaffected.
Current best fix is to either use Alternate Download Mode or a VPN, neither of which are exactly elegant but it is what it is until this gets fixed.