We've never released a public NuGet package for Telerik UI for ASP.NET MVC on nuget.org up till now. I am not sure why your assumption is that such a package existed there.
So far the only option you have for UI for ASP.NET MVC 5 NuGet package distribution is to download it from your Telerik account, under the Telerik UI for ASP.NET MVC section.
Have in mind that we have plans to publish a feed for direct trial and commercial UI for ASP.NET MVC NuGet package downloads in the near future, stay tuned for updates in 2015.
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