Valid from List & Label 20
The automatic NuGet Package Restore is not active in versions of Visual Studio which have been released before Visual Studio 2013.
To be able to run the List & Label ASP.NET samples it is necessary to activate the NuGet Package Restore.
Please open the properties of Visual Studio via Tools > Options > NuGet Package manager > General and check the option "Allow NuGet to download missing packages during build".
After this you have to select the option "Enable NuGet Package Restore" in the context menu of the opened solution.
If everything was configured correctly missing packages should be downloaded automatically if you build the project. Please note that this option can only work with a given internet connection and that the actual process can take some minutes.
You can have a more detailed look at the following link.