Create a new scene or open an existing scene. (Dragonframe will not connect to your camera unless you have a scene open.)
Make sure you have the latest Blackmagic Desktop Video software installed. Dragonframe won't detect your device without it.
In Dragonframe's Preferences | Capture, select Enable Blackmagic module and restart Dragonframe.
You may need to configure the device Input and Connection to match your camera's output. You can do this through the Capture | Video Settings... screen in Dragonframe.
macOS Note: If you have installed the Blackmagic Desktop Video software, and the device is connected, but the computer doesn't detect it, check System Preferences | Security and Privacy | General to see if the application has been blocked.
Proceed to the Cinematography workspace to adjust the camera settings, check focus, and take test shots.