It's like patreon. It's allowed not only subscription but also a one-time purchase. I can't buy your game here, boosty is my the only option.
There doesn't look to be a nice way to withdraw funds from the platform (that I want to use, anyways). Are you able to do anything like Ko-fi? (https://ko-fi.com/deevil) I could accept a payment there and send you a link to download on itch?
I suspect you'd probably face the same restrictions though :(