The Airbnb is at Via Melzo n 6, which has a windowed room and black gates to the left and right of it. I had difficulty finding it, but communication with the host helped.
When entering the building, turn the key clockwise and push the door while it is pressed in that direction. When leaving, press the button near the windowed room to open the black barred door.
The Airbnb looks very nice and well decorated. When I used the shower it seemed to change from very cold to very hot, even when I kept it around the middle, then going back to warm for a while.
The host is very kind and helped when I had difficulty opening the door with the key.