Note this is a hotel. It's a very small hotel occupying part of a floor in a building. When you get the "entire place" in an "apartment," it means a hotel room. That hotel room is very small -- mine had two beds each next to opposing walls, with just enough room between the beds to get out of them; the toilet and sink are in the shower, and overall with the bars on the window it feels a bit like a prison cell. However, the room is clean (there are stains on walls, but nothing felt actually dirty), the place was quiet at night, and the location (once you find the building, which can be tricky) -- is great. The host is also very responsive. Basically this is a convenient, bare bones place to sleep and shower as you explore Hong Kong, and if you don't need anything else, this is a good option.
That said, although the room is fairly cheap, there are actually a lot of cheaper hotels available relatively close by that, as far as I can tell, are at least as good. The extra could be a markup for Airbnb, which I did not previously know could be for hotel rooms.