Login to public live event

I'm not able to login to a public live event from the browser

• I open a browser in private mode.
• Paste the participant link
• I get the page where I can login or access anonymous.
• If I try to connect using, for example, a Microsoft account, I will see teams loading and the go back to the previous page to connect or go anonymous.
• Is this normal?
• Using anonymous is working.

I want to connect to provide my username in Q&A but more important for the log report to know who participate.

Thanks.

UPDATE

=====

Looks like the user needs to login in teams first in the browser (So this external user needs to have a teams paid or free licence or having been invited to a teams), then if he click on the public live event link, he will be able to join.