I want to buy L4D2 DLC, i have game disc, series x, i am having problems. Help Me

I was forced to purchase L4D2 on amazon because it's not available on the Xbox store, i do not have a 360 instead series x. I want some DLC, I followed other question threads and went to xbox.com through a link of an xbox official. I tried purchasing L4D2 DLC through that website, it took me all the way to the purchase confirm processing screen with green lines going in circles then telling me the purchase cannot be confirmed to try again later, i even tried in the game, it took me to the confirm purchase button but just says premium content is blocked for this profile and to go to my privacy settings. i have xbox ult, i have put many years and buck in my account even a time a small phase of vbucks and more to come. like this, my card has money, i have money, i want some game, give me game for my money, why is this so hard for such an amazing classic as this game. please help me, i just want to pay for game bruv, i have the money right nowww.

:)