I'm not trying to cheat anyone. I've already tried to help you by answering your questions to the best of my knowledge, as well as replying to the comment you posted on Steam with the offer of a free Itch key, which I have yet to receive a reply to
As far as I know you should get access as long as you pay the remainder of the price, but if you want a safer answer you're better off contacting Itch support about this stuff rather than the devs themselves