The game doesn't auto-update on itch.io - you have to re-download to get the latest version. And unfortunately, at the moment, the itch.io version doesn't actually work - flagging itself as an "unsupported" version of the game. Which is very much not ok. Obviously.
If you can use Steam (some of us can't), then on the download page, you have the option of redeeming a Steam key, so that might be an option for you?