After you add your ZEN card to Wallet 
on your Apple device, you can use Apple Pay to make secure, contactless payments in places marked with one of the following symbols: 
How to pay using iPhone and iPad:
Double-tap the side button.
When your default card appears on the screen, look at your device to authenticate the payment using Face ID, enter your passcode, or place your finger on Touch ID.
Hold your device in the proximity of the POS terminal until you see transaction confirmation.
How to pay using Apple Watch
Double-tap the side button.
Place your watch in the proximity of the POS terminal.
Wait, until you feel a slight vibration.