Apple Pay Restricted

What do you mean there is no instructions? it says specifically this:

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. 

Those are instructions.

If you can't Verify your identify as explained then you'll need to contact Apple Support.

Follow the steps here: link-> If your Apple Cash account is restricted or locked - Apple Support

Or contact Apple Support directly as suggested by the notification.