You need to complete the goblin quest. To do this, first go to the bathhouse alone (without Alexia). In the soldier's things, you find the item. Then to the guild on the 2nd floor where the guard loses the letter. Then open the door in the city. There will be a lock. The code on the paper is 271. Open it and go down into the mine. For the mission, it is enough to go down, then at the top to the right into the room with explosives. In the same location, on the right, just below, the scroll item Robin needs on the beach is shining.
Then, according to the script, you are caught by guards and saved by goblins. Then you are taken to your house. Then you go back to the city on the right at the top where the crack in the wall was closed by guards and goblins live there. There will be a quest to find a small goblin. He is in a location where he hunts animals. You go to the very bottom of the map on the right side. Then the goblin runs away and you catch him.
Then the goblin chief says that his son wants to learn to speak human and the school will be opened. It is located at the exit of the first village immediately on the right at the top.