apple legacy set up

This document suggests there are almost no requirements as to who can be a legacy contact. How to add a Legacy Contact for your Apple ID - Apple Support

Therefore maybe the issue is on your end, and possibly restrictions you have set:

If an app or feature on your device is not working, it may have been disabled using Screen Time, or by an IT administrator if you are using a device owned by an employer or educational institution. See how to use Screen Time on an iPhone, iPad, or iPod touch by clicking here --> Use Screen Time on your iPhone, iPad, or iPod touch - Apple Support

Related information about how to use parental controls on your child's iPhone, iPad, and iPod touch to restrict access to features --> Use parental controls on your child's iPhone, iPad, and iPod touch - Apple Support

Contact Apple. Click here --> Choose your country or region - Official Apple Support Select your country, then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.

or:

Contact Apple for support and service by telephone --> Contact Apple for support and service - Apple Support