If you are decrypting the traffic it should show up as the app amazon-music which you can just outright block, without decrypting traffic I'm not sure that ID will actually show up. A quick test of the URLs in North America show the following, as a warning I have no idea how these three domains would effect normal amazon traffic.
Just in case someone needs to block Amazon Sample music for a school network. You may try to block the "Streaming Media" category with the help of URL filtering. However, we set up a custom filter using app-id here: https://applipedia.paloaltonetworks.com
Palo Alto access path: live.paloaltonetworks.com/t5/general-topics/how-to-block-all-streaming-videos
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