Compiled verion of the library is distributed via NuGet package. You can download and install the library directly from your Visual Studio with the Package Manager.
If you arn't familiar with the NuGet packages you might want to check this NuGet Overview.
TypeLITE's source code is hosted on Bitbucket. If you want to contribute, fix a bug or just play with the source code, the easiest way to do so, is to create your own fork directly on Bitbucket.