In a nutshell, they are huge apartments, the more people you are the closer together you have to sleep but they are extremely close to the center and (as you can see on the pictures) beautiful.
There are 4 exact same apartments on floor 1 to 4 and I rented all of them for 60 people. There are 2 Bedrooms and 1 Living room. If you count only the beds, this apartment is made for 4 people. If you extend all the couches you get two bedrooms with 4 and 5 sleeping places and 6 people can sleep in the living room (Max 15 people). It ends up being really crowded but for us it was ok as we got even closer as a group.
This being said, the apartments are really great and Julia and Michael have been extraordinary great hosts!! The apartments are so close to the city center that you can easily reach everything by foot. We really loved that!