1. Download the MSIX:
- MSIX x86
- MSIX x64
- ARM64.

2. Install the MSIX: 

Dism /Online /Add-ProvisionedAppxPackage /PackagePath:<MSIX package path> /SkipLicense

3. Manully install Meeting add-in, checking the installed Teams Version "x.x.x.x"

Get-AppXPackage -Name "*msteams" | Select-Object -ExpandProperty Version

4. Transfer the ownership of the folder to Administrators

takeown /F "C:\Program Files\WindowsApps" /A /R /D Y
icacls "C:\Program Files\WindowsApps" /GRANT Administrators:F /t

5. Get the "add-in" version "a.b.c.d"

Get-AppLockerFileInformation -Path "C:\Program Files\WindowsApps\MSTeams_x.x.x.x_x64__8wekyb3d8bbwe\MicrosoftTeamsMeetingAddinInstaller.msi" | Select -ExpandProperty Publisher | select BinaryVersion

6. Create the folder for "add-in" installation: "C:\Program Files\Microsoft\TeamsMeetingAdd-in\a.b.c.d\

7. Install Teams Meeting add-in, choosing the installation folder created in step 6

msiexec.exe /i "C:\Program Files\WindowsApps\MSTeams_x.x.x.x_x64__8wekyb3d8bbwe\MicrosoftTeamsMeetingAddinInstaller.msi" ALLUSERS=1

For Windows Server 2019, New Teams only could be installed by PowerShell Command.

The Teams Meeting add-in will not be installed automatically if Teams is installed via PowerShell.

This article describe how to install the New Teams and Meeting add-in in Windows Server 2019.