Right now you're facing towards a closed glass door. Now turn right, there is an open door in front of you, move towards the door and exit the room. There is a portrait on the wall to your left, move towards the portrait. You can see a staircase in front of you, move towards the staircase and get down the stairs and turn right. You can see a platform to your left and a closed door to your right, move forward and stand in between them and it is your end point.