Bug: Notifications are too frequent and too loud when download file

[Xanonymous-GitHub]

Describe the bug As title.

To Reproduce

1. choose a large file to download (ex: course video)
2. listen! your device will become very annoying!

Expected behavior The download notification show only show once, and contains a progress-bar which indicates the progress of download process.

Screenshots If applicable, add screenshots to help explain your problem.