Microsoft Edge is only available on Windows 10. Due to the current state of Windows 10 on mobile, we have decided to separate testing and supporting of Edge on desktop from testing and supporting Edge on mobile. It's worth noting that we have not officially tested the HTML5 client in Internet Explorer on mobile either. See bug 5780 for support of Microsoft Edge on Desktop.
Windows 10 Mobile is out now. Did a quick test on my Lumia 640 and the HTML5 client seems to work fine.
Windows Phone is discontinued by Microsoft. We will not be supporting this.