I just got my series x and i tried downloading mw2 worked fine but when i try to play on...

As moderator HomegrownSilky mentions, it's correct you need some of those subscriptions to be able to play online multiplayer.

I await your prompt response to continue helping you!

Best regards,
Daniel.

I have already downloaded every content pack for content to campaign and multiplayer & if i remember correctly this was a game bought with a linked account

Hi Otto S! I hope you are well, delighted to be able to offer you my help!

This may mean that you are not signed in with the account where you purchased the game in your living room.

Can you log in to https://account.microsoft.com/billing/orders and check if you can see the game order listed as "completed"? Once confirmed, make sure you are logged in with the correct account.

Also, go to “My games and apps” > Installed games > Highlight the game > Press the Menu button > Go to “manage games and add-ons” > Click on the game icon.

Make sure these packages are installed:

Call of Duty: Modern Warfare II - Content Pack 1
Call of Duty: Modern Warfare II - Content Pack 2
Call of Duty: Modern Warfare II - Content Pack 3
Call of Duty: Modern Warfare II - Content Pack 4
Call of Duty: Modern Warfare II - Content Pack 5
Call of Duty: Modern Warfare II - Content Pack 6

Let me know if this information was useful to you, otherwise I will be attentive to continue helping you!

Best regards,
Daniel.

Do you have a subscription to either Game Pass Core or Game Pass Ultimate? You need one of those in order to play online multiplayer games. The only exceptions are free-to-play games.

It actually seem to be the disc im trying to play if i put another dvd in it works fine which is strange iv tried several discs and they all work apart from this one and if i put that disc in my pc it works fine but it used to work on my xbox one x before i got my series x its not the disc as it works on my pc and actual old dvd player