Using an extended display requires your computer to be in 'Extended setting'. Here's how to make sure you're in extended setting and not duplicate/mirror. Once you've connected the second display via USB-C - follow these few steps.
(1) Display setting shortcut
Hold the windows button and press the "P" button on the keyboard toggle presentation display settings.
(2) Choose the display setting
PC Screen Only - Laptop (primary) display only, even if you're connected to a second screen.
Duplicate - Second screen will duplicate or mirror your laptop (primary) device.
Extend - Second screen acts as an extension of your desktop. You are able to drag separate programs/windows onto your second screen.
Second Screen Only - Laptop display will be [off] and will only be displayed on the second screen.
(3) When connecting via Clickshare with second display.
Clickshare will automatically duplicate your laptop onto the projector.