Forza Horizon 4 auction house grayed out what to do?

I would like to know how to set that I can go to the auction house. I've also heard that you have to change something in the parental control settings on Xbox Live, but where is that on the Xbox website or on the Microsoft website where I have to change something, and I'm also part of a family on Xbox live as with Microsoft Which account do I have to log in with so that I can change what I can also change everything. But you also have to consider that I don't have a console but play on a Windows 10 PC

Alone as a family you have already activated the protection of minors. You have to change this to public somehow