The challenge consisted of an audio file
Upon listening to the sound file it became clear, that it had to be a modem sound, so a program to reverse the data into its original form was required. Intro minimodem. It can be installed in Kali via:
The hints from the hidden track proved quite invaluable as 8 data bits and 300 baud were the same values required to resemble this audio file.
The resulting file was: