Restricted Apple Pay account

• If your Apple Cash is locked or restricted you must go here to start the lengthy process of getting it unlocked or the short process to get it unrestricted - If your Apple Cash account is restricted or locked - Apple Support

Go to your Apple Cash card

• iPhone: Open the Wallet app, then tap your Apple Cash card.
• iPad: Open the Settings app, tap Wallet & Apple Pay, then tap your Apple Cash card.
• Apple Watch: Open the Apple Watch app on your iPhone, tap Wallet & Apple Pay, then tap your Apple Cash card.

You'll see the option to Verify Identity or Contact Apple Support. Tap one, then follow the onscreen steps. Learn more about identity verification. 

1. If your account is restricted, you can still transfer your Apple Cash balance to your bank or use it to make purchases in stores, within apps, and on the web.1
2. If your account is locked, you can't use Apple Cash to make purchases; add, send and receive money; or transfer the money in your account.

also

To set up Apple Cash Family you must first close any accounts that children already had. Make sure that the balance is zero then go here - Manage your Apple Cash account - Apple Support next, go here - Set up and use Apple Cash Family. (Additional support links View and limit your child or teen's Apple Cash activity, Leave Apple Cash Family, Apple Cash and person to person payments limits)