Setting up future meetings with participants using Teams calendar or Outlook integration
"Can I just send an MS teams invitation via MS outlook and expect things to work, or not?" Yes you can.
You can ask the user to the following article to find out how to sign up for MS Teams free: https://support.microsoft.com/en-us/office/sign...
If the users don't want to create MS Team free account they still can join the meeting but as anonymous guests without having an account. Please note, anonymous guests is different from the regular guest, anonymous guests don't need to be added to a Team, unlike regular guests. Anonymous guests can only access the meeting but not the Team, unlike regular guests.
In the following article, I have shown how users can join a meeting as an anonymous guest by using the MS Team Desktop app: https://answers.microsoft.com/en-us/msteams/for...
Whether you want them to create an MS Teams free account or join the meeting as anonymous guests, that's completely up to you. the choice is yours.
Yesterday I have a conversation with other users from China he accesses the MS Team without a VPN. https://answers.microsoft.com/en-us/msteams/for...
Kind Regards