In order to install Telerik UI for Xamarin, you need Xamarin installed. To install it with Visual Studio, you need to choose custom installation and C#/.NET (Xamarin) [3rd party]
as shown in this article
. If you already have Visual Studio installed, you can change the installation, also shown in the same article. If you have both VS 2013 and VS 2015 and installed Xamarin directly from their website, you might need to enable Xamarin for VS 2015, this is also shown in the same article -- look for Are the Xamarin project templates missing
I believe this will fix the problem with the installation.
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