DSLRs do not function as webcams over USB. USB is normally there only for battery charging and to copy files off the SD card.
You will need an HDMI capture device (assuming the camera has a clean HDMI-out port available). Normally these cost around $100-200 for a decent-quality unit, like the Elgato Camlink or HD60S. Before spending, I'd recommend plugging the camera into a TV to check what it outputs; Canon are notorious for 'baking in' the on-screen status display, which means having to crop the image down to 'cut away' the edges so that OSD will not be visible.
Some DSLR manufacturers will offer a 'live preview' over USB to their proprietary software. This is always low-quality and low-framerate... it'll look far worse than even a cheap webcam in most cases.