CityEngine is licensed via the ArcGIS Urban Suite. ArcGIS Urban is an add-on license to your ArcGIS Online Account. To request the ArcGIS Urban Suite, please contact the Map and Geospatial Hub via the Service Request form and indicate that you would like to be licensed for ArcGIS Urban Suite. You will receive the license and a download link to ArcGIS CityEngine within two business days.