Done, I didn't actually know about the app lol. Turns out it was because the downloads were hosted on mega and not on itch. I've put a copy of the public version on itch so now they'll work on the app. Just be sure to select the relevant "(Itch hosted)" file.
Unfortunately I can't make the early access version available on there just yet as I'm currently still affected by the 1gb limit on file uploads. As soon as I can get that overturned, I'll start moving the files to itch hosted for better compatibility.