A warm welcome to Beoworld..
I have had a look at this "Supplimentary Guide" and whilst it is 8 pages in size, it is just four short paragraphs repeated in all the common languages.
It says:-
The following information supplements page 13 in the Guide.
If you use BeoSound 2 in Mass Storage mode, or load the SD card in a PC card reader, the card must be scanned to update the playlist file.
This scan occurs automatically if no playlist file is found on the SD card when you switch on BeoSound 2.
If the playlist file on the SD card needs to be updated, start the scan by pressing and holding both "Down Arrows" buttons for two seconds. During the scan, BeoSound 2 beeps at three second intervals. When scanning is complete, playback starts automatically.
Switching off BeoSound 2 stops the scan. However, this produces an incomplete playlist file.