How can I authorize my child (7 year) to change his birthday.

My son created his apple account with a different birthday information. Now I am trying to set up a family sharing but my son looks like an adult. When he tried to change his birthday information within “apple settings” the system said it is sending an e-mail (to me) in order to authorize that change. I did receive the email explaining the situation about the change within my son’s account. Then, the email says “To approve this change, click Approve Request and sign in with your Apple ID”

Within the same email there is no chance to do it, neither I haven’t received any message on my device to approve it.

could somebody advise me on how to solve this issue?

Thank you,