Hi there! Just to add up to the answer provided by the AI. It's also worth checking the Xbox privacy settings, especially if Roblox is showing a message about multiplayer or access to user-created content. You can have ask your parent to sign in here to manage the settings:
https://www.xbox.com/user/settings/privacy-and-safety
On the page, select the child’s account and go to XBOX and Windows 10 devices Online Safety. Make sure the required multiplayer and content-sharing permissions are allowed.