Windows 8 has had a Metro-style app available for a while that allows Windows 8 computers to seamlessly connect to remote server resources. (You can find that app HERE if you missed it). But, there's been very little available to allow Windows Phone devices to do the same.
The My Server for Windows Phone app provides Windows smartphone users the ability to manage users, devices, and alerts, and it also allows access to share files running on a Windows Server 2012 R2 Essentials server.
To get it, either search the Windows Phone store for 'My Server 2012 R2,' or…
…you can grab the app from here: My Server 2012 R2