The prerequisite for WiiM Mini to be displayed in Amazon music is to sign in to Alexa.

Please follow these steps to resolve your problem:

  1. Go to Browse>Amazon Alexa to sign in to your Amazon account in the WiiM Home app. Please make sure the account of your Amazon Alexa is the same as the one used in the Amazon Music.
  2. Go to Amazon Music App > Playing UI > Tap Alexa Casting icon to check if the WiiM Mini is under 'Select a Device to Play Music'.
  3. If you can't see the WiiM Mini, please wait for some minutes. Amazon Music needs some time to fetch a new device.

The related UI are shown in the below:

WiiM Home

Amazon Music “Now Playing" UI