How to make surfacebody stl printable.

Hello. I am new to solidworks and have recently downloaded an stl file. When I upload the stl file into solidworks, it will only upload as a surface body, not a solid body. I am trying to use featureworks so I can print the file without a "no geometry" response, but the featureworks is only available for solid bodies in the 2017-2018 student edition SW I am using. Does anyone know how I can download this as an sldprt file with geometry to print? I have attached the file below.

SolidworksGeneral