How to Unlock Dawntrial Job Gear in FFXIV

To unlock the dawntrial job/artifact gear in Dawntrial you only have to follow the level 99 main story quests.

Once you pick up the quest In Pursuit of Sphene, Koana will guide you to Mewazunte in Tuliyollal, an armorer vendor. The vendor will let you pick up all the gear for all jobs once unlocked, so don't forget to revisit when you hit level 99 with a new job.

All gear has an item level of 690 and can also be dyed after completing the Dawntrial role quests for the respective role.