You might be asked for the security code on your credit or debit card to verify your payment info. Make sure to update your Apple ID billing address and payment method if anything has changed.
Visa, MasterCard, Discover, China UnionPay, JCB, and Diners Club
Check the back of your card for a three-digit code that's after your card number.
Check the front of your card for a four-digit code that's above your card number.
If your security code is missing or unreadable, contact your bank or credit card issuer for help
If you have an iTunes or Apple Music gift card, learn how to locate your redemption code.
Learn what payment types you can use for iCloud storage, and the iTunes Store, App Store, and iBooks Store.