So… I literally have no clue, and I have to see some dungs on my max level evoker… I went to Zandalar, got greeted from Talanji, got the boat, but the boat has no options to go to Kul Tiras. Nathanos gives one quest to go to Nazjatar, and… that’s it…
its been a while but if i recall the should be some npc you talk to at some docks somewhere wich would take you to horde outposts there. But honestly i dont know the horde locations of these npcs. So best i can say is try the npcs at the zandalaari docks
Edit: i think you got to do the introduction q to the city first to unlock the ferry locations. I remember when i went to kulthiras on my chars the first time you had to do a tour to the most important locations including the ferries to unlock them
As far as I know you need to follow the questline leading up to the pyramid, and once you choose a zone to level in you will get a quest to speak to Nathanos down at the ship.
The quest there should open up the option to set up a base at one of three Kul’tiran zones.