I thought there was supposed to be a free version on here according to the one patreon post I could actually see I have been following the game for awhile and I know I got chap 5 for free from here too!
maybe try a regular download without trying to overwrite files? Just download the full version here if you paid for it. You are probably getting rid of the wrong files, but this game is legit and I have no issue playing the newest release. I bought the update and had no issues installing it and getting it to run so therefore the game works and if you are having issues that means either the download messed up a few times for you or you are experiencing user error.