To download the latest version of your app, call the following function: 
UpdateController.Instance.DownloadUpdate()
The SDK will attempt to download the latest available version, triggering the following callbacks in sequence:
  1. onDownloadStarted: Triggered once when the SDK begins downloading the update.
  2. onProgress: Triggered multiple times during the download process to report the current progress.
  3. onDownloadEnded: Triggered once when the download is complete.
  4. onInstallationReady: Triggered when the update is ready to be installed.