You have to check-in at another building several blocks away. There is no physical key; they use a digital key from an app which you have to download. The digital key did not work when I arrived, and several other guests were also struggling with the app and trying to contact the office in the other building. There is no one in the actual building where the unit is to help you. I finally reached someone through the intercom to help, but she was not polite or apologetic. The unit itself (individual bed) is small but clean. But note there are absolutely no hand soap, utensils, plates, cups, etc. provided. This is very strange for a unit that is advertised as having a kitchen/microwave. The location is close to Cuatro Torres/Chamartin but very poorly connected (due to bad urban planning and construction). Plan on taking an uber/taxi everywhere or walking a long distance to the train station. Overall, I would NOT recommend staying here. There are many other options with better amenities and better location in Madrid at a similar price point. Stay away!