The previous blog explained what needs to be done to be able to deploy and debug apps with latest build for IoT-Core (Build 10586). On the Microsoft IoT forums it was reported by some that if they didn’t set up as in the previous blog they got a pin request. This blog provides some detail as to how the Universal (Unencrypted Mode) authentication works. It also explains why some got the PIN request.
Links:
The previous blog: Win 10–IoT Core- Visual Studio 2015 Update 1 App Deployment and Debug Requirements –1
Microsoft IoT Forum: https://social.msdn.microsoft.com/Forums/en-US/home?forum=WindowsIoT