Xbox does not have permission to play online?

Hello, first it's a pleasure to be able to help you today.

My name is welcome to the community.

Hello Flubber, they are both free to play, what would be your console model and what error message appears when you try to play online?

Have you also checked your online privacy settings?

You have to go to privacy to change this or go to your age my sister has it set so she cant play online games or games made by others to make sure she doesnt do anything so its probally skmething like that

Hello, I've read your question, and I believe I understand your situation. The Xbox Ambassadors are here to help.

Turn on your Xbox,Press the Xbox button to open the guide. Then go to System > Settings > Account
> Family. Select "Manage family members" and then find your kid's name and select "Access to content," then select the age limit you feel is appropriate for your child.

if there are 2 separate Microsoft accounts you can make his console your home Xbox

setting > personalization > my home Xbox >
make this my home Xbox. or just buy that account an Xbox live subscription.

which basically is saving you a receipt to your console. allowing him to access games and subscriptions on your account without signing in and can be used on his profile without purchasing a game you already own again.

Yeah going to the privacy settings on the xbox while on that account should sort this out. As it sounds like a child account you will probably get a prompt to log in with your account in order to change their settings. After that it should all work wonderfully
and you’ll all be gaming together in no time