How it looks - it looks like you are used to
Use your Spotify app - output device: Player
Use any other app on your phone or tablet (as you always do)
Stream with Bluetooth, Airplay or even UPnP
Access the Player software - it is easy to use
Start page - web page: player.local*
Connect your Bluetooth Speakers or Headphones
Manage network connections
USB playback . . .
*) If you are using an Android device your browser may understand http://player.local and open the start page as intended. Unfortunately, most versions of Android OS are not capable of resolving a local web address. Instead you have to use the IP address of the player instead. How to find the IP address is described here.