This achievement is simply obtainable by completing the 404 storyline. The 404 storyline is unlocked during progression of the main campaign and really shouldn't be missable if you get far enough in the story.
There are 4 missions in the 404 storyline and it goes as follows:
- Initiate Sequence
- 404 Not Found
- Coming Home
- Into The Void
The description of the achievement may show but at the moment (as of 30/10/2020) it says "This achievement is a secret. The more you play, the more likely you are to unlock it!"
Please leave comments/replies if I did anything wrong. Feedback is appreciated :)