That has been bugged for months. I have tried it what feels like a billion times but it doesn´t unlock. Hopefully it gets fixed when H3 drops for PC and the next update comes along.
Recruit - Onyx
Made your first hot drop into HaloWaypoint.com
View your Service Record on the web.
Become a member of an active Spartan Company.
Awarded to players of Halo: Fireteam Raven.