If an app or feature on your device is not working, not appearing, or is restricted (grayed out), it may have been disabled using Screen Time, or by an IT administrator if you are using a device owned by an employer or educational institution.
- Read this support article If your Apple ID or other options are greyed out in Settings —> If your Apple ID is greyed out in Settings - Apple Support
Tap Settings > Screen Time > Content & Privacy > scroll to Allow Changes.
- If the device is managed (Settings > General > VPN & Device Management), contact the IT department that is doing the managing.
Read the document:
Sign in to your iPhone with Apple ID - Apple Support
- Make sure you are signed into your account
- Verify payment method(s) and billing address as described in Add a payment method to your Apple ID - Apple Support . Items in red have problems.
- If you're using other Apple IDs with services such as Messages or the App Store, make sure those are signed in too.