In the meeting, set the option (tested)
https://support.zoom.us/hc/en-us/articles/202828525-Allow-participants-to-join-before-host
https://support.zoom.us/hc/en-us/articles/205172555-Using-your-host-key
https://support.zoom.us/hc/en-us/articles/360028478292-Live-streaming-meetings-or-webinars-on-YouTube