Help with Waypoint Armor

Does anyone know how to unlock the Reach armor from waypoint? I’m trying to get all the armor, and I just completed a few of the achievements needed, but it still says they’re locked. There used to be an update button, but I don’t see it anymore. Any suggestion?

I know the armor takes 3 specific achievements each that have to be completed to unlock them. some achievements that you need are from other Halo games. I have some unlocked , but still have a couple of pieces locked, so depends on which “few achievements” you have unlocked

Ya I went back and got a couple of the achievements from ODST to complete the armor requirements but it still hasn’t unlocked it. It doesn’t even show that the ODST achievement has been completed

Pretty sure its through milestones, complete achievements on games to raise your milestone number. Then it unlocks in the armory. Go to waypoint and view reach armor, it will give all the achievements related to unlocking the piece. Hope this helps.