Super Easy Setup.

Get the Alexa App

1 - Set up your Alexa device using the Amazon Alexa App

2 - Open the menu, go to Settings, then Music

3 - If Spotify is not set up, tap 'Link New Service', select Spotify

4 - Link your Spotify account to your Alexa account

5 - Tap 'Default Services' and then select Spotify as the Default Music Library