I have Dragon Age II Standard Ed. How do I get Legacy and MotA DLC on EA app?

On the game page in my library it says "Standard Edition", I want to play Legacy and Mark of the Assassin DLCs. But I see no way to get them on the EA app. When I click Manage Add-ons it just shows Black Emporium, High res pack, and Promotional Pack. DLCs doesn't show up on the search either. How do I upgrade or buy the DLC? 
I tried this page but when I run the downloaded app it says DA2 needs to be installed. But it is installed. Help please