mate...don't you know how Itch work?
click on "install" then once the download screen pop up, click on the "insall" case, and there you'll see there's the 32 bit default version and the 64 bit ^^ have fun. I wish i could even play this game at all but with my graphic card dead... that's a bit nope for me ahah... it looks fun, albeit a bit complicated. Wish i'd seen the kickstarter... would have so invested in it
also, in fact you even have on this very page the "download" section with all the different versions, aka : linux, mac, 32 and 64 bit ^^