[NAME]  What specific HP laptop are you using?  Video output from a WD19 requires that the USB-C port support video output, called DisplayPort Alt Mode.  (USB-C always uses DisplayPort output even if an adapter/dock later converts that signal to HDMI.)  That is an optional capability on USB-C ports and therefore it not implemented on all systems that have USB-C ports.  Did you check the specs of your specific laptop to confirm that its USB-C port is specifically mentioned as supporting video output rather than being a data-only port?    
I've lately bought a WD19 dock to extend my HP Windows 10 laptop display to two Dell monitors. Both monitors work when plugged directly into the laptop's single HDMI port one at a time. The dock doesn't seem faulty, it has power, connects the keyboard and mouse through USB and I've tried a replacement. However, neither monitor will work through the dock, whether connected by HDMI or DisplayPort (I bought an adaptor after seeing the other posts recommending it was the way to get dual monitors working). I've updated the laptop BIOS and tried re-installing the Realtek drivers and firmware update, but still can't get the laptop to detect the monitors via the dock. Error message when connecting says 'the USB device malfunctioned and windows does not recognise it'. I'm about ready to return the dock unless anyone has bright ideas?   Thanks.    
WD19 dock problem: no monitors detected