Such a silly format to include in a 2018 box set. As if we all have our cassette players hooked up to our main systems in this day and age.
Jarre, get a grip. Your music needs to be on LOSSLESS BD~A in 5.1 or Atmos.
I saw him live a few months ago and respect him immensely. The cassettes are an artifact and novelty. Not too far from the marbles in the Pink Floyd boxes. There is no question in my mind that there was supposed to be a DVD/Blu-ray in this set with the 5.1 mixes (the download includes an "intro" video with no audio that would be the loading screen on a digital media and is meaningless in this context. and the Dolby Digital+ encoding was obviously intended for a DVD). Someone said no to it, but thankfully allowed the download.