When your device (for example Notebook or Tablet) has a USB-C port, then it is not guaranteed that a video signal can be send over this port.
To use this functionality, the USB-C port of your device has to support Display Port Alt Mode (DP Alt Mode) or Thunderbolt 3.
When the “DP Alt Mode” or “Thunderbolt 3” is supported, this is often printed as a logo next to the USB-C port :
DP Alt Mode
When this logo is not visible next to the USB-C port, please look into the manual of your device. If the information cannot be found in the manual, please contact the manufacturer of your device to ask if “DP Alt Mode / Thunderbolt 3” is supported.