MainActivity.cs

    public class MainActivity : AppCompatActivity, IOnMapReadyCallback, ClusterManager.IOnClusterItemInfoWindowClickListener
    {
        public Dictionary<string, ClusterItem> m_dicAllMarkerOnMap = new Dictionary<string, ClusterItem>();

        //...

        public void OnMapReady(GoogleMap map)
        {
            //...
        
            //Initialize cluster renderer, and keep a reference that will be usefull for the info window's click event
            m_ClusterRenderer = new ClusterRenderer(this, m_map, m_ClusterManager, m_dicAllMarkerOnMap);
            
            //Custom info window : single markers only (a click on a cluster marker should not show info window)
            m_ClusterManager.MarkerCollection.SetOnInfoWindowAdapter(new CustomGoogleMapInfoWindow(this, m_dicAllMarkerOnMap));        
        
            //...
        }
    }