Error: You are not authorized to access this content

If your account is a child account you will need your family member to go over the steps mentioned here to grant you permission: Grant an exception to your child’s content limits | Xbox Support

If the account is an adult account, you can adjust your settings in case you have any restrictions here: Manage Xbox online safety and privacy settings | Xbox Support

You did not "lose" your downloaded content, you were banned and that means that you cannot access the content that you bought. Regardless of cost, you signed a contract saying that you would not mod your xbox in any way and that should an issue occur,
you would send it in to a Microsoft authorized repair place, which you did not.

That code means that the content is not available or when the payment is not authorized.. The game you are trying to purchase is only available through a Credit Card. It is not available to purchase with points at this time so that is more than likely why
it is giving you that error.

Yes, per the terms of use they can remove content at any time.

2.5. What limitations apply to my access and use of Microsoft and third-party content? We may disable access to Microsoft and third-party content associated with your account for any reason. We may also remove or disable games, applications, content, or
Services on your Authorized Device in order to protect the Services, application providers, network operators or any other affected or potentially affected parties.

It might be looking for authorization to link your account. I'm not sure that you can manually add the "approval", there are APIs that the app should be using to ask to access parts of your Microsoft Account and prompt you for that authorization. You
can check what is currently authorized for your account at your Microsoft Account page,
clicking on Privacy at the top, then scrolling down on that page to the part for "Apps and services that can access your data". That page will have a list of apps that are authorized to access your Microsoft account.