Iv completed all 4 campaigns required to get the armour and i still haven’t gotten it
Go back to MCC. Change a customization item (emblem, banner, multiplayer armor, etc.). Make sure the game saves the change. May also help to play 1 multiplayer game. Then open the Halo Channel app (may not help but can’t hurt). After all that, go back to Halo 5 and check your REQ collection to see if Helioskrill is unlocked.
Thank you Chimera30 for helping me it worked