This is currently in Preview – planned to release very soon.
In the following weeks, Teams will be rolling out support on Safari 11+ on macOS. While in preview, there are known issues with Safari’s ITP mode and it is advised that users disable Safari’s Intelligent Tracking Prevention.Troy commented
"Frustrating that Microsoft Teams is unavailable on Safari, especially if someone does not use Google Chrome/Firefox.
A release sometime soon would be great. It's 2017."
WHAT A JOKE, IT IS 2019!! and still no teams on mac safari..... now it seems it will be rolling out in the coming weeks.... probably months.... and there is some mumbojumbofiddling to be done to het it working still...