If arriving via Milano Centrale Station I would suggest an Uber for circa 19 Euro to the apartment. I think the walk would take 15 minutes and at night I would not be comfortable to do so in that area.
You need a mobile phone with data to access the website that opens the gates to the apartment and the inner complex initially - keys provided once within the apartment. It's a secure environment and the rooms are clean, well equipped and spacious.
The tram stop is outside and the cost of an Uber from the apartment to Duomo di Milano (the main Catherdral and plaza) is circa 25 Euro.
Lots of graffiti spoils the area in this central location.
Host very responsive.