How to login to Xbox Live?

I’m working on a UWP game for Windows 10 and Xbox One. The game is built on top of SDL2 2.0.5 and works like a charm on both platforms. My problem is connecting to the Xbox Live features using C++. I found a lot of info on accessing various features using C++\CX and C++\WinRT . Does anyone have an example of an SDL2 app logging in to Xbox live?