Why does Alexa state 'Spotify not supported on this device'?

Why does Alexa state 'Spotify not supported on this device'?

Voice control of Spotify is not supported on E300, but the service is available via Spotify Connect, simply open the Spotify app, find some music you want to listen to, then tap on the devices icon (small speaker) which will reveal a list of available devices.  Choose your E300 system which you may have renamed from the list, and once selected, tap on play. See also 'FAQ - How to use Spotify'

An alternative is to use Amazon Music which is fully supported.