If you are having issues with Microsoft Teams Meeting Addin missing in Outlook, here are a few tips:

  1. Make sure Microsoft Teams Meeting Addin is installed and present in the Control Panel
  2. Navigate as admin to:
    • C:\Program Files\WindowsApps\MSTeams_23320.3021.2567.4799_x64__8wekyb3d8bbwe (Version number might have changed)
    • Copy MicrosoftTeamsMeetingAddinInstaller.msi
    • Run the following command:
      • msiexec.exe /i “MicrosoftTeamsMeetingAddinInstaller.msi” ALLUSERS=1 /qn /norestart TARGETDIR=”C:\Program Files (x86)\Microsoft\TeamsMeetingAddin\1.23.33413\” (Version number might have changed)
    • Also, make sure this key is set on the user side. You could make a GPO or Intune script for that
      • HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\Outlook\Addins\TeamsAddin.FastConnect
      • “Description”=”Microsoft Teams Meeting Add-in for Microsoft Office”
      • “FriendlyName”=”Microsoft Teams Meeting Add-in for Microsoft Office”
      • “LoadBehavior”=dword:00000003

References:

https://www.reddit.com/r/MicrosoftTeams/comments/18gwkrb/workaround_for_teams_meeting_outlook_addin_not/