If you're using Office for Mac, see Microsoft Teams installations on a Mac. In the future, you'll be able to install Teams along with Microsoft 365 Apps in GCC High or DoD environments without needing to use the separate MSI-based installer. For links to the correct version of the MSI-based installer for your environment, see Install Microsoft Teams using Microsoft Endpoint Configuration Manager.
Instead, you need to install Teams by using the separate MSI-based installer.
If you're in a GCC High or DoD environment, currently you need to exclude Teams from being installed with Microsoft 365 Apps.
