The following help item is shown:

User

To enable this feature for your own use:

1. Sign in to the Zoom web portal.
2. In the navigation panel, click Settings.
3. Click the Meeting tab.
4. Under the In Meeting (Basic) section, verify that Join different meetings simultaneously on desktop is enabled.  
5. If the setting is disabled, click the toggle to enable it. If a verification dialog appears, click Turn On to verify the change.
   Note: If the option is grayed out, it has been locked at either the group or account level, and you will need to contact your Zoom administrator

However, I am a single end user not in a corporate setting.  While I can see and open the In Meeting (Basic) section there is no Join different meetings simultaneously on desktop option present to enable?

Is that option available to single basic end users?

Very basic question.  We are a non-profit, and we are about to get a a paid account to have various volunteers conduct meetings over the summer when other volunteers (who have Zoom licenses from their jobs) are not available. 

So a very basic question -- can we have multiple user names sharing the license (we understand only one meeting can be active at a time).   Is there a master user name so I can create and delete these  other user names over the summer so as prevent people from scheduling a meeting without clearing it with me (and creating embarassing confusion.) 

Thank you. 

When two of my meeting guests try to register and enter their email address, they get a message that says, "This meeting is for authorized registrants only. Please enter another email address." Everyone else has been able to register with their email addresses so far.

Is there any way to add the two people whose email addresses the system is bouncing myself? I tried to register them using the same link I gave everyone, and I got the same error message.

Thanks for any advice!