Hi there FamilySharing98,
We understand you're trying to get a new iPad set up for a child, and we'll be happy to help.
It sounds like during the iPad setup, you created an Apple ID for your child with a birth date that makes them 13 years of age or younger. This age would require that child Apple ID to be attached to a Family Sharing group. In order to set up and manage Family Sharing, you would need an iOS device of your own, or a Mac where you can sign in with your personal, newly created Apple ID. The following page offers additional information and guidance on this: Set up Family Sharing
Alternatively, if you know a family member or trusted friend that has Family Sharing set up already with room for another member, they could invite your child to their group instead.
We hope this helps!