In case you use DNN Community or Professional edition v5.2.0 or later, you will receive RadControls for ASP.NET AJAX as part of the distribution (read about the partnership between Telerik and DotNetNuke here
If you want to use our controls separately or with previous versions of DotNetNuke, consider using the stand-along DNN modules we have (see the enclosed screenshot). Also refer to the third bullet under the 'Support' category on this page
the Telerik team
Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items.