After more experience with Google Meet I have rewritten this to better describe the major problems.
If you use multiple email addresses, you can run into problems when people invite you to Google Meet sessions. The invitations are (understandably) keyed to the email address used in the invitation, so when you click on the invitation it automatically tries to sign you into that account I have found two distinct modes of failure.
If you have multiple gmail addresses, Google opens your default browser and signs you into your default gmail account. The default is the first gmail account you open in the browser. If you open your personal gmail when you turn on the browser, that’s the default browser. If later in the day you have a Google Meet invitation to your work email, clicking on it takes you to your browser, but your personal email is still selected, so you can sit there waiting endlessly until you manually convince Google that your business email is the preferred Google account. It can take a few minutes to figure out that’s the problem.
If your Google Meet invitation is to a non-Google email which is not registered with Google, you run into the same problem. When it first happened to me, I tried to register that email with Google but I was blocked and told I could not create a new gmail account that does not use a gmail address. I have yet to find a way around that problem other than telling people who invite me to Google Meet to use one of my gmail accounts.