Distribute macOS installer as a drag and drop DMG
I'd be open to using Teams for collaborating with outside organizations, but to install Teams on macOS, the outside person will have to have administrative privileges on their mac. When they don't, we can't achieve intended results.
In contrast, Teams for Windows can be downloaded and run without admin, and Zoom.us and GoToMeeting distribute applications than can be directly run, without requiring privileges to run an installer app.
Ted Goddard commented
This is an important security feature.