Use the full client experience Microsoft Teams has clients available for desktop (Windows, Mac, and Linux), web, and mobile (Android and iOS). These clients all require an active internet connection and do not support an offline mode. To profit from all benefits of Microsoft Teams whenever possible use the desktop client on your local machine. Using other methods (e.g. virtualized environment, web, ..) can result in a poor end user experience.
Make sure that the new meeting experience is enabled Teams -> Settings -> General -> Check “Turn on new meeting experience�