Usually you don't have to do this manually, but in case the Visual Studio solution fails to do it: Download the windeps.7z package and extract it into your DarkRadiant working copy (the directory you cloned the sources into).
Usually you don't have to do this manually, but in case the Visual Studio solution fails to do it: Download the windeps.7z package and extract it into your DarkRadiant working copy (the directory you cloned the sources into).