It appears Amazon is seeking to allow those with accounts to upload music to a cloud storage location and play the music from that location. Under Amazon’s system, you need to have an account and are given 5 GB of storage for free. In order to upload your music, you need to use the Amazon MP3 Uploader, a free helper application that finds your music and playlists and uploads it to the Cloud Drive.
You need to agree to certain terms and conditions and download the MP3 Uploader.
It does not appear that there is an app available for the iPad to upload or play the music. It will be interesting to see if uploaded music can be streamed to your iPad via a browser. Meanwhile, the service appears to be available to those running the Android system.