PS5 "You can't link to a child account."

Trying to link my son's subscription to his PS5 and keeps giving me the error "You can't link to a child account."

My son have full access with no restrictions on the playstation network, and after contacting Playstation support they said there is nothing on their end and I should contact apple support. On the apple support page it says nothing about age restriction on the app. My son is 15, and uses apple music on the phone flawlessly.

Please help.