Unfortunately, our check in didn't go smoothly. Right after our landing at the airport, I tried to contact with Agustin, as he asked, but there was no answer. We managed to talk to him only after we arrived to the apartment and realized he is not in Germany, however, I didn't get from him in advance the number of the contact person that was supposed to wait for us.
In addition, the person that opened the door for us eventually was the cleaning guy, that was still doing his work.
However, during the following days, all of our requests were answered quickly. The apartment is nice, clean and in a central location.