3D PRINT SETTINGS:
The STL file is already oriented properly.
The model is "full", that's totally normal.
You have to "emtpy it" by using one of the methods described below:

I recommend to print it in vase mode (see settings below):

For a 0.8mm nozzle:
• activate "vase mode" (spiral vase or spiralize)
• Layer height: 0.4mm/layer
• Line width: 0.8 to 1.5mm (it works ;-)
• Bottom shell layers: 3

For a 0.4mm nozzle:
• activate "vase mode" (spiral vase or spiralize)
• Layer height: 0.2mm/layer
• Line width: 0.8 to 1mm
• Bottom shell layers: 6

Or you can print in regular mode (not vase mode) with a 0.4mm nozzle and 2 to 4 wall perimeters.
Just make sure to cancel the infill and cancel top layers so you actually end up with a cup.

I also added some fuzzy skin to add some surface texture:
• fuzzy skin point distance: 0.6mm
• fuzzy skin thickness: 0.25mm.

Happy printing!