Using Classic Outlook on Windows for personal email, calendar, and contact management
for over a month now, the .msi from the addin has been part of the new teams installation. you can extract it from the installation folder. theoretically, a machine-wide installation is possible. however, this did not work for us.
but what does work: define an applocker exception. then the .msi is automatically installed in the user context when the new teams is executed.
you can find the details in previous posts on this topic.