Hello!

I've understood that you can start the DLC by talking to the Soroborean caravaneer, by saying "I want to travel with you." I own the DLC, yet I have no such dialogue.

Is there some minimum quest that must be done to start it? Do I have to start a new character to see the new dialogue?

Same issue Found the solution, theres a separate setup.exe in the downloads folder of the game. Trying it now

Heh.

Apparently the DLC had loaded, but wasn't activated automatically. I had to manage installation --> configure to activate it.

So now the starting screen changed, the new dialogue options are there. I can activate the "Enrollment" quest by asking about the Acadamy. The quest directs me to ask the caravaner to take me to Harmattan.

When I ask to travel with him, he replies that he's not travelling anywhere at the moment.

There is indeed a minimum requirement. You need to have cleared the first main quest (i.E., repay the 150 silver within 5 days or lose the lighthouse). Once you get the quest to join a faction, the caravanners should be willing to take you to Harmatten (which will cost 200 silver and 2-3 travel rations).

Hmh, I have already done that.

Apparently he now offers the option to travel, though. Maybe he just doesn't want to travel at all times?