You need to tap Continue and sign in to verify your billing information.
Verify your payment information or *** add a new payment method.
To verify your payment information, you need to Sign in to your Apple ID account page and edit / update your Apple ID details -> https://appleid.apple.com
On the Sidebar click Payment methods -> then tap Payments Methods and tap Manage payment method.
Or *** -> Change, add or remove Apple ID payment methods
Change, add or remove Apple ID payment methods – Apple Support (UK)
• If you want to change your card, add first the new card, then remove the old one.
• or if you use your Apple ID balance, set your Apple ID balance as your default payment.
If you update your payment method or add funds to your Apple ID balance, It would take about 1 to 3 business days in order to process.
If you're still unable to update your payment method, Contact Apple Support.
Click here for more support and assistance.