I purchased a plugin from Envato at https://codecanyon.net/item/audio-players-addons-for-visual-composer-wordpress-plugin/19292250/support

Clearly, the expectation was that I was purchasing the audio player and playlist plugin. When I open the "Unlimited Addons" plugin that was installed from the dowloaded file, the addon I purchased does not appear. Very, very frustrating.

Oh gosh! Ok, I found it. I didn't realize that it required two installations. Thanks.