A Microsoft platform for building and publishing apps for Windows devices.
You must compile as x64 if the OS is x64 : there is in the doc at Radio.GetRadiosAsync :
When this method is called from a desktop application (Win32), it will retrieve radio instances only when the application is natively compiled for the target architecture
(in other words, when the application matches the computer architecture; so an x86 application running on an x64 architecture computer won't see any radio instances).