Sorry to bug you again, but it seems that the game page links to a MEGA URL, which the itch.io desktop client is /also/ unable to handle.
If you care to, it should be possible to upload and host your game files on Itch directly; if the files are both hosted on Itch /and/ marked with the appropriate OS flags, it should (in theory) be possible to use the itch.io desktop client to download the game without having to use an alternate web browser.