That seems to be one of the only logical answers at this point.
If you haven't tried already, you could refer back to your email for the email you get for purchasing the game and continue from the download page provided there, or download the itch app and download from there, although I have a feeling you've already tried all of that. I'm sure the developer will fix the problem soon.
Edit: Im glad it worked for you, Scratch the mac problem, I hope everybody else has the problem resolved.