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 

Additional Settings

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.