Everything is OK. The apartment is spacious, very clean and bright. It's 2 mins walk to Chamartin train station. It's not the place where someone lives, just typical apartment for rent so it looks like hotel room tbh. I'm not even exactly sure how this market works (especially if the owner is a private person or just the city of Madrid) but some apartments are officially for rent.
Pedro, the guy who cares abt the apartment is nice, very helpful, bit pedantic, lives nearby and always eager to give you an advice abt the city. The communication was very good, he replied our messages really quickly.
Overall - recommended if you need privacy and quiet place.