Is it not aloud for a person under 18 to add a card in Apple Pay

Issues with Wallet/If you have trouble adding a card to wallet

Device configuration

1. Start by going to settings>general>reset>and reset all settings.
2. Turn off your device and turn it back on.
3. Force reboot your device (Force reboot device - Apple Support)
4. Sometimes if you sign out of your Apple ID and back in it resolves the problem.
5. Make sure you are using the latest iOS/macOS update.
6. Make sure that your date and time is correct under Settings > General > Date & Time.
7. Make sure that you are connected to a known-good network and are not connected to a VPN.
8. Make sure that push notifications are set up correctly: Use notifications on your iPhone, iPad, and iPod touch.
9. Make sure that your zip code is accurate under Settings > [your name] > Payment & Shipping.
10. Check your Apple ID region to make sure it is correct. If it is correct, you may need to select the same region again. (Change your Apple ID country or region - Apple Support)
11. Check the region on your device to ensure it is correct (Settings>general>language & region - set to your region). If it is correct, you may need to select the same region again.
12. A passcode is required to use the Wallet app. 
13. You need to be in a region that supports Apple Pay - Countries and regions that support Apple Pay - Apple Support
14. Your bank needs to support Apple Pay - Apple Pay participating banks - Apple Support

Error messages/messages

• If you get an error that your card is in the Wallet but does not appear go to icloud.com>sign in>go to account settings>select the device>remove Apple Pay from the device>Sign out of your Apple ID>restart the device>Sign back into Apple ID>set up Apple Pay again
• If you get an error that you already have the maximum amount of cards in wallet with less than 12 cards (iPhone 8 or later) 8 Cards (all models earlier than iPhone 8) signing out of your Apple ID and back in usually resolves this issue.
• If you are getting a message to contact the card issuer, call the bank or credit card company who issued you the card to make sure there are no restrictions on the card. 
• If you are getting a message that Apple Pay services are unavailable at this time, sign out of your Apple ID and back in.

Device procedures

1. Once all of that is completed go to these links - Adding credit or debit cards to Apple Pay - Apple Support, Set up Apple Pay - Apple Support
2. If none of these suggestions are able to resolve your issue you can go here for further assistance - If you can't add cards to Wallet for Apple Pay - Apple Support
3. Apple Pay support can be reached here - Apple Pay Customers

Additional information

• Add, use, and share boarding passes, tickets, and other passes in Apple Wallet, please note that passes cannot be directly added within wallet, except for QR code enabled passes. For everything else, its done either through the associated app, an email, airdrop or a link in a website.
• If you need to change your default payment in Wallet or have other issues such as the inability to add passes you can go to these links which covers managing Wallet and wallet use.

Related links

• How to use Wallet on your iPhone, iPod touch, and Apple Watch - Apple Support,
• Manage the cards that you use with Apple Pay - Apple Support
• Add an e-Money card in Apple Wallet to use with Apple Pay - Apple Support
• Set up a Suica or PASMO card in Apple Pay - Apple Support
• Add a Disney MagicMobile Pass to Apple Wallet on your iPhone - Apple Support
• Add a hotel room key to Apple Wallet on your iPhone
• Unlock your home, car, and hotel room with keys in Wallet on iPhone - Apple Support

THat's because your parents are over 18...