The address provided leads to a hostel, where you will do the check in. Afterwards a staff member brings you to a separate building which is 100m away. The location is great, just a few metres away from Roma Termini.
The room is on the second floor (there is an elevator), you'll need four keys to get to the room, the first two doors can be a bit tricky to open.
The room itself is very basic, but the bed was comfy I slept well. However, it's not really soundproof so you could hear the neighbours and outside noises. There was also a somewhat unpleasant smell at the beginning but that went away after a day.
The bathroom was clean, but the shower head bracket was broken so I had to hold the shower head in my hand while showering. The water pressure was quite low. The toilet flush button as well as the bathroom bin have also seen better days.
Personally I wouldn't stay there again, but for a short stay you should be fine (especially if you want to be close to the main station).