Apple cash
Sending and receiving money is restricted
Welcome to Apple Support Community!
If your Apple Cash account is restricted or locked https://support.apple.com/en-us/HT207932
You will need to speak to an Apple Cash advisor, they will transfer you to an Apple Cash specialist to hopefully get your Apple Cash unrestricted.
You will not be able to send or receive money in messages until you have your Apple Cash account unrestricted.
Contact Apple Support https://support.apple.com/en-us/HT207959
Hope this helps