I use only one single USB-C cable to charge and to transfer video and sound data to the monitor. The USB-C cable needs to be of good quality, that is with all circuits loaded. A simple USB-C cable which is only designed for charging purposes will not do the job.
All in all it works flawlessly like a docking station for my Mac Book

I use HDMI for picture and USB-C for charging. That works fine, except that my laptop then thinks there are two monitors connected. I haven't yet figured out how to transfer image and power with USB-C.