Hey there! Thanks for the interest in the game. :)
In case there is some confusion, there should just be some PDF files. This is a tabletop RPG, rather than an app. Which may explain why it's not showing up in the installer. (I realized I had the "Games" category, rather than "Physical Games" selected).
Offhand, I'm not 100% sure where PDFs go in the Itch installer, but I did just see the files on the game page. But let me know if you still can't get 'em, and I'll see if I can send them another way.