How do I get the add on cars after buying the add on? And the missions are not popping up in the quest menu.

1 Answer

The DLC will only unlock as you progress through the game. If I remember correctly, most of the DLC such as the cars and outfit packs will unlock after you complete the Escape mission requiring you to break out of the simulation.

The missions, however, require further progress such as obtaining the Telekinesis superpower for How The Saints Saved Christmas.