Setting up parental controls, having problems...

I’ve set up a device with family sharing/parental controls on 2 devices for my children. On both of them it won’t allow me to download an app... even a kids app without purchases.

it prompts for the child’s Apple ID. Then password. Then it asks for Apple ID again and I’ve tried re-entering theirs and mine and it then says it’s incorrect. It never once prompts to ask for parents permission or anything... what am I doing wrong?