Dante Virtual Soundcard is a way of getting audio from your computer to the Dante network and vice versa, utilising a standard ethernet port on the computer.
If you need to do that, and you don’t have a Dante device specifically for this, (e.g. the RedNet PCIe card, RedNet 5/HD32R to interface with a Pro Tools rig or a Red Range interface) then YES, you need Dante Virtual Soundcard.
You do NOT need Dante Virtual Soundcard to use Dante Controller.