Hi
My name is Daniel. I am an Independent Advisor and consumer of Microsoft products, I will be more than happy to help you.
"What is the most simple process for allowing people (who do not have a Microsoft Teams account) to register and connect via Teams?" You can add users as guests to Team, you can work collaboratively with them without needs for them sign up for MS account. Please
visit these links:
https://support.microsoft.com/en-us/office/add-...
https://docs.microsoft.com/en-us/microsoftteams...
"Also, is it possible for them to automatically enter once they have the event number/password or am I required to allow them in one-by-one?" If users join a meeting as guests then they don't need to enter a password but the host needs to admit/approve the
guests in order for them to be able to join the meeting. Users also can join the meeting from web browsers without needs to install the MS team desktop app. However, if a user wan to join a team/channel as a guest then she/he needs to enter a password.
Video on how to join a team as a guest:
https://support.microsoft.com/en-us/office/join-a-team-as-a-guest-928d1eef-61e2-49ec-b754-c2fe86b34824
Demo video about the live event in MS Team.
https://www.youtube.com/watch?v=pGmdfUL5mGU
DISCLAIMER:
The link above is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products).
Thoroughly research any product advertised on the site before you decide to download and install it.
Kind Regards