To start the missions of this DLC, look for the yellow bull head which has an anchor on the world map.
There are only 2 missions in this DLC, being:
- The Setup
- The Heist Begins
As soon as you've completed the 2nd mission, this one will unlock.
You will notice throughout these missions that there are some Eden Callaghan Tapes (18) to collect.
There is no achievement related in collecting them all, nor something extra.
Just some background info on Eden Callaghan such as with Di Ravello.
You can collect all these tapes after the missions and will be shown on the map as with the other collectibles.
Some people report this achievement as glitching/not unlocking!