I found the instructions, which weren’t 100% clear, in the readme.txt file. . . imagine that ??
I did have to go into display settings and click ‘on’ across from ‘Show Buy Text’. I then added the word “Download” into the ‘Buy Text’ field. Then on the actual playlist sound tracks, I gave the URL to that MP3 file in the field ‘Link Buy Text’.
Hope that helps someone!