Our experience in this app was not so nice, mildly put.
Hans the owner was very nice, however we had quite unpleasant communications with his wife Nanette, which did not make us feel welcome already before coming.

In summary our experiences:
1) The app in not on the ground floor as advertised but is a sous-sol, half underground
2) The pictures on the website do NOT reflect the real experience: it is dark as there is almost no natural daylight, even with all lamps on it is permanently dusk, very depressing
3) The sous -sol app is very humid, blankets and mattress are moist and smell of fungus
4) No fresh air can come in as even if you open the windows so there is no air circulation
5) Although the mattress is of an OK quality, the beds are tiny and a bit inclined due to the floor
6) The second morning the bathtub was filled with 20cm of urine due to a problem with the sewage system
7) All supplies left in the app were minimal, literally, so the last 3 mm of washing liquid, 1 cube of detergent, 4 cups of coffee and no soaps at all.
So you could start your stay buy buying everything yourself in a already expensive app.

We decided to leave and booked a hotel instead, which has plenty of natural daylight, in a peaceful neighborhood and with free breakfast, which is even cheaper than this app, which was rather expensive.