If you are referring to a PIN number, I think it's for purchases yo make over a certain amount with your room key. You can just swipe the card at RFID scanners and I think you need the pin for purchases over $50. Seems like that is what I remember from being there in January. Someone please correct me if i am wrong.
^^^ that is exactly why it asked you for a pin. They no longer swipe your KTTW card for purchases. Basically the new system allows you to just hold your KTTW card up to a scanner.
They had just added this feature to POFQ the day we checked in (last Thursday) so the CMs were learning! We had to enter a pin for any purchase we made using our room key regardless of price point.