Apple has released macOS Catalina 10.15 beta 4 to developers for testing. The building number is 19A512f.
Run MacOS Developer Beta Access Utility to download the latest macOS beta. When new MacOS beet becomes available, you will receive a notification and can install them from the Software Update pane of System Preferences.
With MacOS Catalina, Apple replaces iTunes with new Apple Music, Apple Podcasts, and Apple TV apps. A new Sidecar feature lets users expand their Mac desktop by using iPad as another monitor or as a high precision input device. New security features keep users better protected and Voice Control lets users control their Mac completely with their voice. You can learn more about macOS Catalina here.
Developers can download Beta Access Utility from the link below. Please follow iClarified on Twitter Facebook Google+ or RSS for updates.