Hi Eager! ☺️. You need to put the code when you play the game too
I have the same problem. I have been liking the game so I bought the code, but in my save file the galleries and scenes are still locked after entering the code. Playing on mac.
[Edit: I found you have to 'start' a new game. You can then select the chapter and fast forward to where you were before. It's a bit difficult but it works.