There are two types of collectibles that can be found within the Exodus DLC.
Classified Intel: These are randomly picked up from searchable items, and their locations change during every playthrough. You will need to pick up a total of 4 of these intel types to unlock them. Only 1 player can pick it up, and it will automatically unlock the intel in order. Each area will contain between 1-2 intel items, and this can easily be boosted solo using the first area and then dying during the first drill section.
Encrypted: These are also permanent laptops that can be found on the map, and their locations are as follows:
1. The Final Option - Go right from the first spawn area, into the hut, and find the laptop on the bed.
2. Caller ID: Unknown - From the first spawn area, go through the middle gate, turn left and use the blue crate to get on top of the truck to find this intel.
3. More Than Human - From the parking garage, use the exit door nearest the first generator (to the right of it), follow the hall, and once getting outside, you will find it on the ground near a construction table.
There is also an Epilogue and Top Secret intel, but it is not required for the achievement. To find the Top Secret / "Always Hard" Intel, see the video below:
COD: Ghosts - Top Secret Intel / "Always Hard" - Nemesis DLC - Location, Tutorial & Guide