Cassandra was flexible with the check-in and check-out times. She was helping me to find the place at arrival, and welcomed me with the keys.
The location is quite good, but you still need to take a train/tram, or walk 25 minutes to reach the core of Friedrichshain with all the restaurants etc. The apartment is located in a quiet courtyard.
The apartment was super clean and well organized and also quiet. The room had everything I needed.
I recommend this place to everyone.