Itch.io has the sandbox mode as standard activated. A lot of VR games don't connect with steamvr or occulus in this mode.
With right click on the game and click on open folder in the menu -> itch.io navigates to the installtion directory of the game with the file explorer of windows.
Open the game with click on the exe e.g. \itch\apps\physical-checkup-vr\Physical Checkup VR\Physical Checkup VR.exe
This works and it's a little bit safer than deactivating the sandbox mode for all games.
You can scan the exe-file with a antivirus tool to be a lit bit more on the safe side.