Ana is such a sweet woman who waited to greet me at the studio. It is very small, just one room (and a bathroom), but has everything you might need. The WiFi is very good.
We stumbled upon some difficulties, but together with Ana we fixed them all. Truly one of the most helpful and kind people I have encountered.
The studio is situated very near the train station Atocha and at a great location.
Pro tip: use the Lime/Bird scooters, which will get you all over Madrid in only a few moments :)