CWIS (EWS on this product) doesn't exist when it is hooked up via USB to a PC, there are no network features in that case becaus eit isn't on a LAN.
It did not support scanning via USB cable, only scan to Network, (and it sounds like it isn't on one) and scan to USB stick, which is already working in fact it is still listed that way officially on Xerox.com. But since there is indeed a Scan to USB driver listed for the product, it may have been added after release, in which case you would likely need updated firmware, the latest version is here. I looked at the release notes, it doesn't list it as being a feature added
But my guess is that the driver should not be listed for the product (it was posted in error)