All online bookings at Adelaide Airport now use QR codes to enter or exit the car park. You can scan your QR code by either opening the email on your phone, saving the QR code to your mobile wallet, or scanning a print out of your booking confirmation email.
If you choose not to pre-book your parking, you can enter the car park by tapping your mobile phone/digital wallet at the entry gate and then tap the same card again at the exit gate.