Very strange. Just double-checked again, still working fine for me, but it's clear you're not the only one who's had this issue. At least it seems to be somewhat limited, but I hope Itch gets their shit together. Downloading a game and having it just NOT WORK is a really bad first user experience, and it risks turning new players off instantly. Also I'm not a high IQ, high-paid sysop, but how hard is it to have FILE DOWNLOADS work in current year? I thought that was pretty much a solved problem for at least the past 15 years. With the exception of a handful of oddball situations, I haven't had download corruption be a major problem since I was downloading over dial-up in the late 90s.
The other thing that baffles me is that it's CONSISTENT. If I'm understanding you right, you've tried to download it multiple times, back to back, and it breaks EVERY TIME. Which is...wild.
That said, steer clear of anything fancy, the Itch program or whatever they call it. Just download direct if you aren't already. Hope you have better luck eventually, and if they still haven't fixed this in a few days, let me know and I'll be sure you get a copy one way or another.