Add Store to Windows 10/11

I actually recommend ThioJoe Windows Sandbox Tools Microsoft Store install script. It way better than this and use Windows Update API which is alway up to date when you run it (it doesn't have AppInstaller and Xbox Identity Provider tho)
If you still want to use this, download latest version here
For Windows 10 Enterprise LTSC 2019
Download

To install, run Add-Store.cmd as Administrator

Addition troubleshooting

Right click start
Select Run
Type in: WSReset.exe
This will clear the cache if needed.