Newly created child account is not activated

I created a child account for my son from my iPhone 15, creating an @icloud.com email address, and linked it to my my own account within the family sharing settings.

I then set up my son's iPhone 8 SE using the newly created child account.

The next day, I realized that none of the parental settings are syncing between the devices. I also realized as I was troubleshooting that I couldn't log into the new child account on his phone (or icloud.com) using the email & password that I'd set up.

The message I received back was "this account is not active". I tried recovering my password on icloud.com, but the message I received was "this account is inactive. Click here to request a reactivation. This will take a day or more to process". I clicked on the link, but since then (4 days) I still haven't been able to log in.

Help! Did I miss a step somewhere? Do I need to create a completely new child account? How can I find out what's going on with the other account?