How to verify my Apple ID?
How I verifiable My apple ID account
[Re-Titled by Moderator]
iPhone 6, iOS 12
See if adding a payment method to your Apple ID as outlined in: Add a payment method to your Apple ID - Apple Support is what they mean by "verify".
On an iPhone:
Open the Settings app.
Tap your name.
Tap Media & Purchases, then tap View Account. You might be asked to sign in with your Apple ID.
Tap Manage Payments.
Read the support article for how to do this on other platforms.