This will work as a standalone. Unleashed will NOT work.
If you want some sort of Unleashed support I would recommend R500 as a minimum WAP. If the area of coverage is small, R310 would do just fine.
On a side note, this is a 2.4 GHz ONLY, N-radio WAP. Unless you collect vintage stuff, this is not a great WAP compared to what is available on market today.