How to launch a game?

You need to buy the base game , or you can subscribe the EA access,

That's a game add on mate you need the base game that's why you can't launch it

Since that is an add-on to the base game, you would need to purchase the base game as well in order to play it.

I would try contacting xbox support and arguing your case as you are right, you cant have played it if you dont own the base game

You can try replying to the email you received denying the refund in order to speak to the refund specialists, or try submitting another form, but otherwise all you could do it use the item is buy the game itself.