Hi Kilganon,
We’re not very familiar with the Itch.io desktop app, sorry. But you don’t necessarily need the MEGA desktop app to download the game. It does make it faster and easier, this is website in case you want to try that. Otherwise if you visit our page through your browser, you should have no issues downloading the game either, with or without the MEGA desktop app.
We will try to get in contact with itch.io to address this issue however, so you or other future users don’t experience this same issue. We hope this helped and you are able to download the game now though. Otherwise please let us know and we’ll think with you for a solution.
Love, Team Oopsy Daisy