FamilySharing not working

Hi, I purchased Anki mobile app with my Apple ID and enabled familysharing with my 14yrs’ kid, but no matter what I try it’s always going to cost another $29.99 for my kid to download the Anki mobile App, does anyone know what could be wrong and how to correct? I clearly read there is familysharing up to 6 users allowed with the purchase. Thanks!

Please see Reinstalling - AnkiMobile Manual