You should download your Windows Server ISO images from TechNet/MSDN and place them in this folder. We need to do this because MSDN / TechNet are protected by Microsoft (Live) ID, which does not support HTTP basic authentication or the OAuth2 username / password flow.
For example, you might want to start with one of the following:
* Direct Download: http://msdn.microsoft.com/subscriptions/json/GetDownloadRequest?brand=MSDN&locale=en-us&fileId=44782&activexDisabled=true&akamaiDL=false
* Direct Download: http://msdn.microsoft.com/subscriptions/json/GetDownloadRequest?brand=MSDN&locale=en-us&fileId=44783&activexDisabled=true&akamaiDL=false
* Direct Download: http://msdn.microsoft.com/subscriptions/json/GetDownloadRequest?brand=MSDN&locale=en-us&fileId=50539&activexDisabled=true&akamaiDL=false
* Direct Download: http://msdn.microsoft.com/subscriptions/json/GetDownloadRequest?brand=MSDN&locale=en-us&fileId=50573&activexDisabled=true&akamaiDL=false