If you are unable to add your YouTrip cards directly via your Apple device, you may go ahead and add via your YouTrip app:
Note: You will not be able to add a YouTrip card via Apple device if the card status is 'Lock'
1. Open your 'Cards' tab
2. Select the card you wish to add
3. Tap on the 'Add to Apple Wallet' button to be directed to your Apple Wallet
Learn more why I am unable to add my YouTrip cards via Apple device
How to add your YouTrip cards to your Apple Watch