Using Hyperdeck Studio mini as Web presenter

We are using the SDI input on the Hyperdeck to generate a HDMI output which works well. We also want to simultaneously use the USB-C output as camera input to ZOOM but that does not work. However the Hyperdeck manual indicates that it should work. ZOOM indicates that there is a camera there as "Blackmagic design" but not "Blackmagic Hyperdeck". Can anyone give us a clue how to solve this problem?