How to set Firebase Database URL (Unity)

public void FacebookLogin()
    {
        var perms = new List<string>() { "public_profile", "email" };
        FB.LogInWithReadPermissions(perms, AuthCallback);

        if (FB.IsLoggedIn)
        {
            
            string aToken = Facebook.Unity.AccessToken.CurrentAccessToken.UserId;
            Firebase.Auth.FirebaseAuth auth = Firebase.Auth.FirebaseAuth.DefaultInstance;

            Firebase.Auth.Credential credential = Firebase.Auth.FacebookAuthProvider.GetCredential(aToken);
           
            auth.SignInWithCredentialAsync(credential).ContinueWith(task => {
                if (task.IsCanceled)
                {
                    Debug.LogError("SignInWithCredentialAsync was canceled.");
                    return;
                }
                if (task.IsFaulted)
                {
                    Debug.LogError("SignInWithCredentialAsync encountered an error: " + task.Exception);
                    return;
                }
                
                Firebase.Auth.FirebaseUser newUser = task.Result;
                Debug.LogFormat("User signed in successfully: {0} ({1})",
                    newUser.DisplayName, newUser.UserId);
            });



        }

       
    }