Just to close this off, it looks like for the WD19TB to work on a non Thunderbolt USB-C port the USB-C port must support DisplayPort. 
HI, I've got a Dell WD19TB that I use with my XPS 15 which works great.  I've purchased another laptop for the kids (I didn't want them playing on the XPS).  The new laptop is a new model this year with a USB-C 3.2 Gen1 port (AMD Ryzen 5 5000), from the documentation on Dell's site I was under the impression that the WD19TB would step down to USB if it didn't detect a Thunderbolt port and it would still work.  However when I plug the WD19TB into the new laptop get one chime confirming that the USB port has detected something but nothing works i.e. the USB devices plugged into the WD19TB don't work, neither does the external monitors.  I've upgraded the firmware on the WD19TB to the latest in the hope that would help but alas it still doesn't appear to work. Am I missing something? are there some extra drivers I need to get the WD19TB to work on a non-Dell? Any thoughts or help gratefully received.  
WD19TB - Not working on non-Dell laptop