Are the windows/mac builds not working? The itch app should still be able to run the demo of the prologue too, is that giving you any issues?
I can download them through the download page, but since it isn't marked for windows, I can't just click update.
You need to add the operative system on the upload (old picture but should look similar).
When done correctly, you should be able to see the windows/mac icon next to the files here on the game page.