I downloaded it from the web link as well. It was a 3.whatever rar. Unpackaged, the folder is 5.7 Gigs. I think Itch uses extra space for unpacking and storing into its UI for ease of use (like how we click 'update' to do updates through it rather than downloading an entirely new version if not through the app) or something, which is weird because that is like 2 gigs extra space!