The DSLR can be connected to your computer through a variety of ports—ranging from HDMI to USB. In this walkthrough, I'm using a Nikon D5200 connected with a USB-A to AV port cable.
When your camera is connected, launch digiCamControl. There will be a preview of your feed in the application window. From the left-hand pane, select the Start Live View button.
Your computer will now recognize your DSLR as a webcam input device.
At this point, you can use the webcam feed however you see fit. It will work with most video conferencing applications like Zoom or Discord. It even works with streaming tools like OBS.
Just launch the software you want to use and set the webcam device to your DSLR camera.