This utility is used to create individual audio files from recorded music streams (MP3 files) using meta information (CSV files) into individual audio files over an overall folder (CD).
There can't be any legal discussion about recording audio files here. Recording (not downloading!) MP3 files (e.g. via Audacity) from streaming providers is legal (contrary to what is stated in the providers' GTCs), at least in Switzerland, as long as it involves making private copies. According to German case law, files recorded in this way may be made a maximum of seven copies for archiving purposes.