It seems to be something about the certification, if you tried apply to music on your alexa device, maybe you must attempt creating another without music application.
If that's not the case you could try deleting everything and downloading again from the oficial github.
Remember that ProductID is the one you entered as "Device type ID" on the first step on registering your device. Do not put double quotes nor single quotes, spaces, dots, etc. If you select the text from amazon developer console and paste it on the nano command look carefully for not selecting any white space before or after, sometimes even if we can't see it, for the pc there exist a space or a new line character.
Make sure that the product id in product scope URL parameter is exactly same as the product ID you used while registering (it will be indicated as "Application Type ID" or "Device Type ID")
I spent half an hour for this issue and putting the right product ID fixed it.
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