MainPage.cs

public partial class MainPage : ContentPage
{
    public string CastUrl { get; set; } = "https://icecast-qmusicnl-cdp.triple-it.nl/Qmusic_nl_live_32.aac";

    public ObservableCollection<IReceiver> CastDevices { get; set; }
    public IReceiver SelectedCastDevice { get; set; }

    public Command StartCastCommand { get; set; }

    public MainPage()
    {
        InitializeComponent();

        Init();

        StartCastCommand = new Command(StartCasting);
    }

    async void StartCasting()
    {
        var sender = new Sender();
        // Connect to the Chromecast
        await sender.ConnectAsync(SelectedCastDevice);
        // Launch the default media receiver application
        var mediaChannel = sender.GetChannel<IMediaChannel>();
        await sender.LaunchAsync(mediaChannel);
        // Load and play
        var mediaStatus = await mediaChannel.LoadAsync(
            new MediaInformation() { ContentId = CastUrl });
    }

    async Task Init()
    {
        // Use the DeviceLocator to find all Chromecasts on our network
        var receivers = await new DeviceLocator().FindReceiversAsync();

        CastDevices = new ObservableCollection<IReceiver>();

        foreach (var r in receivers)
            CastDevices.Add(r);

        BindingContext = this;
    }
}