Oh gosh, I'm so sorry to hear that you're running into that bug! Which OS are you running the game under? Are you running the game in any sort of sandboxing software?
that has caused some issues forsome players - try just downloading the game from the store page normally without the use of any Itch client and that should work, though try running itwith admin access just in case there's some permissions issue preventing it from writing the save file to your filesystem.