Why don't USB ports on Dell P2721Q not work?

[silverlakerCA]

I was hoping to drive my Logitech webcam from one of the monitor's two ports instead of the precious few Mac Mini ports.
Nothing works.

Any ideas that's wrong? and how to fix it?
Thank you.

 

[hg.wells]

What cable are you using to connect to the display?

You need to be using USB-C to USB-C for the data transfer piece. Any other cables like USB-C to HDMI won’t work.