it is a mesh. a polysurface would be an array of NurbsSurfaces joined together. just to be sure there is no misunderstanding, to print it you dont have to go that way if you dont have to do any nurbs specific adjustment to the geometry.
first explode all parts that you can see what you have.
problem nr 1
your object is only 0.09 mm big, i guess that is even for the finest printer not possible to print, you might have messed something up while importing it. you can use Scale to rescale the object to a more appropriate size.
problem nr 2
in the image below i highlighted a part of the mesh which is not a volume at all, its simply a flat mesh joined with the rest. this one would have to be made into a volume with
some parts of the mesh can be joined into closed meshes so its not utterly hopeless, still it needs a bit cleaning up and maybe offsetting mesh etc till you can booelan it properly together. use the
What command on each part to determine if its a closed mesh.
these parts are all open, to quickly close them use
FillMeshHole that will help you in boolean the parts together.
i also found one disjoint mesh you might have to get that fixed either. if you are stuck just call again, have fun.