I didnt see a download for the DLL but the source is there. Download the source and compile your own DLL in Visual Studio. Then put that DLL into Unity and Bobs your uncle.
Nope, thats the Nuget Package which is not what you want. you need a DLL. As far as I cant tell the only options would be to install the Nuget package to an empty VS project and copy the files or download the source and build you own DLL.