If you still didn't get the ending read this
So first you steal on the small shop you should get 40 rupees and a gun now go deeper in the forest and go right then left then another left and left again then you should see the monke HQ but first go in the shack to get the modification for the gun now go to monke HQ and click any of the choices then you should encounter the giant gorilla attack him then attack the monke king and there you go