How to obtain a retainer

[Anubis_Nephthys]

No.
You get access WAY before you choose a GC. You have access. It was something Milfina talked about.

Go to a marketplace and talk to the NPC by the "Summoning Bell". (I forget what the NPC is called.)

[Laduca]

To do this, you must visit the market wards in any of the three major cities. In the market wards, look for the NPC located behind a desk, with the Retainer Vocate tag. Interacting with this NPC provides information on retainers and begins the process of obtaining a retainer.

[Onishin]

My level is a bit missleading lol, I have just obtained access to Satasha Dungeon, I kinda went nuts on over-leveling before doing the main quests >_<;.... but I do have access to the airships and all that stuff so I'll check it out if I can, because I have a ton of stuff I wanna sell.