That is certainly weird. As far as settings on our side go, everything seems to be fine and there's nothing in place to stop anyone from dowlaading it. And I just tested all the download links and they seem fine to me. What kind of window or message tells you it's prohibited? Something from Itch.io, or could it be something else? Which version are you trying to download?
there is no multi-volume. That sounds like an issue with corrupted download or something. Or, if you used a USB drive to move the .zip from another machine, possibly unplugging the USB drive without safely removing it first.