Integration under android

Hello! I'm a student programmer, so I probably have a stupid question, but I do not understand it.
I'm writing projects under unity3d and pretty well figured out how to use signalr for an application on a PC. Just drop the dll in the "Plugins" folder and it's ready. Now the crux of the matter. Where can I find the library for the application on Android? Usually they are in the .so format and I drop them into the Plugins / Android folder and everything works. But SignalRClient.so and anything like that I could not find.
I understand that you can download the sourse code and somehow compile it and get a .so file. But I still do not understand this and ask for help me and integration of the application on android.
Thank you for your attention, the text was written using "GoogleTranslate". I'm from Russia-.-