It could be because I haven't pushed any changes to the beta branch directly (I will once the Patron stuff for May goes out at the end of the month) because I didn't want to break old save games for people yet.
If you go to the main itch.io page directly and scroll to the bottom where it says "demo," there should be four options depending on your operating system. Do you have any ad blockers active or javascript disabled? If so, whitelisting itch.io should help.