The app must continue to download content if the user removes the headset.
When a user removes their headset, the foreground app is paused, which means any downloads running in the app are also paused. In order for downloads to continue when a user removes their HMD, they must be done in the background. To meet this requirement, you can use Android DownloadManager, or other similar utilities, to download in the background.
Download notification is visible.