Oh I totally understand the exit just being a time issue, I think its worth it to point out such things so you may know for future :)
As for how to make it run in itch, I honestly know only the complete basics to game making, and I know actually nothing about unity gamemaking, so I wont be able to help you there much unfortunately. The "play game" button simply doesnt appear on the app, but appears fine on a browser. I found someone with the same problem, but no solution unfortunately https://itch.io/t/91788/embedded-html5-game-not-showing-in-itchio-app