I think the free builds are currently also gated behind purchasing the game. I'd like to try it out!
It still looks like the free build requires a purchase, when I view it in either the browser or the itch.io app. I was able to get an older free build from your patreon, though. 
Whichever settings you have for After Thunder appear to separate the purchase and demo successfully. Not sure what the difference is.
24 days ago(+1)
Thanks for posting again. I don't know what happened. I had those set to be 0. I think the new like demo option they have is making it weird. I made the change. Let me know if its working as it should now.