How to Update a WPF / WinForms Apps Published in Microsoft Store With C# Update Code

Question

I have WPF and WinForms , published privately for now, in the Windows Store which will download and install to a client PC but have not been able to receive the published updates. It is my understanding that the developer needs to provide this update functionality in the application which I have implemented with the provided GetEasyUpdates() method at https://learn.microsoft.com/en-us/windows/msix/store-developer-package-update which unfortunately does not work. (see below)

The following error occurs from the downloading operation a simple test WPF application.

Would really appreciate some help.

Thankyou.