As long as the person is part of the Zoom account, I can assign them and they can enter the meeting as a co-host and they will receive an email notifying them that they have been added as a co-host. This is how I have historically been able to add co-hosts prior to starting the meeting. If you click 'Show', a few additional options pop up, including adding alternative hosts. When creating or editing a meeting, there is a small link at the bottom, under 'Audio', next to 'Options', that says 'Show'. If you have further questions, please reply, we're happy to help. If you find this information helpful, please click on 'Accept as Solution'. If, on the other hand they are first signed into the Zoom client, then click on the link, it does know who they are and it can check to see if they are already registered, and if they are it can simply send them directly to the meeting.

If they are not signed into the client app first when clicking on a URL link to the meeting the system doesn't know who they are, so it has no choice other than sending them to the registration page. The last idea that I'll share is to confirm that they launch the Zoom client application first, then sign-in to the Zoom client app, and finally join the meeting. You could also try sending them the Meeting ID and Meeting Password, rather than sending them a link to the meeting. Co-hosts can only be assigned by the Host from within the running meeting. If I'm reading it correctly it sounds like when are creating a meeting you are also assigning co-hosts to that meeting? If this is true, this is where my confusion begins, as it is not possible to pre-assign co-hosts to a meeting.

Zoom host a meeting login