That's because the files are bigger than my allotted itch.io bandwith, so I host them somewhere else and simply provide the links.
I know I should contact support to see about getting more, but I think that means I'll also have to pay a monthly fee, which I can't afford right now. The game is barely making money.
I'll look into it if I ever reach the 2nd Patreon goal of $250. Glad you like the game though! :)