Straight forward achievement, an outpost houses two generators. Once both generators for a single outpost are operational the achievement will unlock. The generators are positioned around the map in sets of two and each gets subsequently more difficult.
You will need to protect the generator from Cryptids but more importantly the Ancestor which deals a lot of damage. Make use of nearby traps, especially the new Tesla traps which are really effective.
There are six generators, two for each outpost, so three outposts, and can be done in any order.