For all those still having issues getting Teams to launch, I tried deleting the temp files, credentials, rebooting(obviously), etc. The only fix I've found to work is to uninstall current version of Teams, install an older version(I used this version: https://microsoft-teams.en.uptodown.com/windows/download/2267739). It will then prompt you to update, follow the update link and install the most recent version of Teams again. I've had this work for 3 users so far.
