Brief description of your issue
Both the main README here and the documentation on learn.microsoft.com/en-us/windows/package-manager/winget links to a form that does not seems to work anymore.

Is this intended or has the Windows Package Manager Insiders Program been shut down?
the links for the forms are:
https://aka.ms/AppInstaller_InsiderProgram
https://aka.ms/AppInstaller_Unsubscribe