Cannot get "Updating packages deployed using an App Installer file" to work

[jbennink]

I coipied the code from this page but cannot get the line

PackageUpdateAvailabilityResult result = await package.CheckUpdateAvailabilityAsync();

to work. VS keeps saying

Also I had to change the AddPackageByAppInstallerOptions.ForceApplicationShutdown into AddPackageByAppInstallerOptions.ForceTargetAppShutdown but the first thing I cannot fix?

What is going on here.

P.S. Iused the winmd file from the Program Files (x86)\Windows Kits\10\UnionMetadata\10.0.26100.0\Windows.winmd