NPC requires renown 43 to upgrade to level 4 or 5, currently i have renown 44 but i still can’t upgrade
You have to pick up a quest at 43 renown at your sanctum’s renown keeper to go to Oribos to unlock the PvP upgrade ability.
The upgrades don’t automatically unlock just because you met the renown level. It’s been this way for all the PvP gear upgrades for renown, so I doubt this is the first time you’ve seen this quest.
I haven’t played since Wrath and didn’t know why I couldn’t upgrade my gear with more than sufficient renown as well. But I did find the NPC at my covenant sanctum. Easy enough.