So i have been having a lot of issues with this mess of a race unlock, i made several tickets to the wow support team.
And now haven spoken to several Gm`s, i have gathered extra information and i am making progress into this unlock now..
If you are an alliance char, and have the Mechagonian threat achievement, the embassy quest should just be there...Skip all and go unlock.
But if you have done the Mechagonian threat on the Horde side(i did this), it is far more complex and real big pain in the butt....
As i understand i need to do this, if you seen no quest giver at the embassy...use the following method:
1. Get to BFA - use the boat in SW harbour.
Note you may have to go between Boralus - Sw, and back...once the "get to Borallus" quest is activated. And you will have the portal to Boralis after doing the intro quests- Remember to skip the beginner quest(or not) to speed it up.
2. Start doing quests, and pick your zone- once the quest to speak to Taelia unlocks, by using the map.
3. Get 3 reps to friendly and complete Nation United Achievement- you MUST have this!
4. This should start the GO SEE MAGNI - this is the KEY to it all, if you do not speak to him and do his quest chain - NOTHING WILL UNLOCK!
5. Start doing the mother quests for the heart achievement - The Heart Forge- after doing this, you will be sent to Nazjatar to do the the starting quest "Scouting the Palace" in Newhome (Horde) or Mezzamere (Alliance).
Once completed, you should get the reward "Unlock World Quests" reward.
Note: as soon as i did this gnome on a mechastrider rode up and told me to go to Boralus, and talk to the gnome next to the flight path.
6. After speaking to him, this triggered the Legend of Mechagon questline, do the quests in the vault, and go back to Boralus.
7. Meet Gila in Boralus, at the FP and do A Small Team Quest in the town. This leads to The start of something bigger. Now you can hop on the gyro copter, which flies you to Mechagon!
8. Head into town after crash landing, and talk to the prince, then ride the mechaspider to the junkyard.
Start killing things- and USE THE DRILLER BOT- to free Pascal. This is needed to progress.
9. Start the Rustbolt Resistance quest chain, light up the sky with the sign and fight off the flying unit. Then head into town.
10. This now triggers WELCOME TO THE RESISTANCE & Urgent Care
This Sends you back to Boralus