If you've interacted with at least one trial in a region, you should be able to start the Recruit Passcode Specialists mission from the bulletin board. The quest has notable hints such as finding a ship with locked containers and an emphasis on 'followers' and 'putting faith in religion.'
The shipwreck, where a passcode is needed, is in the southwestern corner of the Wasteland region. The required symbols come from altars, which can be visited in any order but are outlined following in-game numbering.
Collection
[
|
...
]