Could you tell me which version of Demons Within are you playing? Is it 13.0? 14.0? Or 14.6? You should be able to see the game's version at the bottom of the main menu of the game
Oh, that's the problem. Chapter 3 of the collaboration on the Demons Within side is only available in version 14.6, which is currently only available for Patreon supporters! I'm working on Update 15 right now, though, and as soon as Update 15 is released for supporters, version 14.6 will become public and free, and then the password will work. :)