Their latest Windows version has some weird DLL blacklist which blocks the ffmpeg DLLs used by the virtual camera. I made an inert version of the DLL[1] but this will break screen sharing due to a set of digital signature checks Zoom does before screen sharing.

https://twitter.com/R1CH_TL/status/1243734261628383232

You need to downgrade Zoom to 4.6.7: https://github.com/CatxFish/obs-virtual-cam/issues/78

didnt work for me either, I had to use NDI tools