You can use the download attribute to force download and JS to automatically click that link.
document.getElementById('download').click()<a href="https://scontent.cdninstagram.com/t51.2885-15/s640x640/sh0.08/e35/23279358_143343893084349_1681002671546302464_n.jpg" download id="download">Download begins</a>3
solved How can I download pictures from a URL to a local computer without asking permission?