Just to add to the above solution
If you look directly under the name of a piece of equipment it tells you the class.
For this achievement you must craft either a full set of Scarab or Gorgon armour.
If you find that you are missing specific materiels for example the components to craft the legs, then you must target enemy legs and pick up the drops. When you visit the medbay go to the crafting table and all of the body parts you collect are crushed into components.
I thought I should add this as I only ever targeted the head or body and never had the components to craft other parts.
Also pressing right on the right thumbstick allows you to craft higher level equipment so if you have no mark 1 components check your mark 2 and 3 components