here is your super female body in Solidworks 2016 version. To get there I opened and on the right there are all the files then I chose STL then option and graphics body then it works
I just tried, I have the bust but how can I transform this bust into a volume piece or other to be able to do for example a removal of material in places?
Your mesh has defects that prevent any conversion to solid.
The thighs are 2 meshes that intersect, which means that when I imported it, it converts the common part into volume.
plus a hole in the base.
I had roughly 4-5 surfaces that are useless.
If you have time, load it on a 3D max (in this student / free version) or a blender (I don't know if it processes the stl) and correct the mesh and remove the inner faces of the bust.
After I don't see how to "rework" on it with SW since he refuses to do any operation on it.
NB: your mesh consists of 792,718 facets for solidworks