Spotlight Cam Pro wired loose

I have just installed the Spotlight Cam Pro Wired. Mounting plate, wiring etc all without difficulty and solid. However it looks like the camera itself is only held on by the usb-c wire? There is a knurled screw above the wire, but no hole on the camera to screw it into, and there seem to be no other screws or holes. What have I missed? One of the installation guides says removing the battery cover before attaching the camera, then replacing it “locks” it onto the bracket, but that seems to do nothing to hold it secure.