Which version of the app are you running? (You can find out by hovering the itch logo in the top-left corner).
Can you open Preferences => Advanced => Open app log, and paste the full log here?
Viewing post in Nothing is installing?
Just installed it yesterday so I know it's the latest version, it also tells me so on startup.
Full log: http://pastebin.com/j4Uh2qeJ
Ah, so it looks like the issue is just with "City Racer" :)
Looks like it's an external uploade hosted on Google Drive, which isn't supported by the app. I left a comment to the developer with instructions on how to fix it: https://skipyc.itch.io/city-racer/comments