question

If you mean using Facebook SDK for Unity, then I'm afraid this is impossible as this SDK only supports platforms of WebGL, Unity Web Player, Android and iOS.

Basically, the problem here is how to use Facebook Login in a Unity standalone project. Once you can login, you will be able to get Facebook access token. And when you have this token, you can then use it in LoginWithFacebook method to finish the login logic.

Although, you can Manually Build a Login Flow for Facebook Login. but you'll need to be able to embed a web browser (sometimes called a webview) within the app to perform the login process. This is the traditional way for windows application, you can have a try in Unity. For problems about Facebook Login with Unity standalone project, I'd suggest you ask on Facebook or Unity forums.