Apple Pay for a child under 13

I've created a special sub account for my child (under 13) at my bank and ordered a contactless debit card connected to this account then sent a small amount of money to let my child use it. IOS refuses Apple Pay to use this card ???? WHY ??? (I can't add this card to ApplePay)

I want to control where my child is spending my money, but I also want these transactions be safe. Using Apple Pay on my child's Iphone8 is much more secure than a contactless card in hand .....

How to bypass this restriction as I want my child to use Apple Pay !