The apartment is fine to stay at if you’re only going to be there for a couple of days. There is just the things that you’ll need and not much more.
It was easy to get the key with the information sent.
The downside/things you’ll need to be aware of is that:
It’s not very close to Madrid centrum and there is also a 15 min walk to the nearest metro and supermarket.
There is also A LOT of noise from the other neighbors in the building and from the water pipes.