Hello huffman.klo3,
Thank you for using Apple Support Communities. Currently, your child must use Family Sharing to make purchases. Those purchases must then be approved by the family group organizer.
If Ask to Buy isn't properly working, we have a helpful resource you can review. These steps should be able to help sort this issue out: If Ask to Buy isn't working - Apple Support
If you're the family organizer, you can go to your Settings or System Preferences to see if your family members' accounts have Ask to Buy turned on.
On your iPhone, iPad, or iPod touch
1.) Go to Settings.
2.) Tap Family. If you don't see Family, tap your name, then tap Family Sharing.
3.) If you're the family organizer, make sure that Purchase Sharing is turned on. Then you can tap a family member's name to see if Ask to Buy is turned on for their account.
There is some more steps you will want to review within the resource we just shared. If everything is properly set up across all linked devices and each device is fully updated, consider reaching out to Apple Support for assistance. You can check for an update by tapping Settings > General > Software Update: Update your iPhone or iPad - Apple Support
You can use the following link to reach out to Apple Support to further investigate the Ask to Buy issue: Get Support
Thank you for using Apple Support Communities.