Thanks for the reply!
I'm unzipping the demo like you said and opening this file:
After that I get a message saying the file can't be opened because the developer cannot be verified (which is normal and happens for anything I download on itch.io), I go to my settings to bypass this message, then when I try to open the file again it just crashes after a few seconds.
Let me know if there's something I'm doing wrong - I'm on OS Catalina by the way.