This seems to be a trick by Digitec. The software can be downloaded (by entering the serial number), but it cannot be activated. For this, the software would have to be purchased additionally.
Unfortunately, I fell for it. After a long back and forth with the software company (with good support), I finally got the following message:

We are sorry to hear that you are having problems activating our software. We apologise for the inconvenience.

Please note that the software requires a licence key. This is printed on the Quick Start Guide. The serial number of your software starts with R7 followed by a number-letter combination. An example of the format of a licence key is: R709Z-XXX-XXXX-XXXX-XX. The licence key is included in the original packaging and can be seen in the yellow box on an insert such as the one attached to this email. Please check the original packaging for this licence key.

If you cannot find the licence key in your package, it is more likely that it is not a package containing the software. Nevertheless, you can use the free trial version of the software, which allows you to run the programme up to 5 times.

PS: On the quick start guide provided by Digitec, there is then precisely NO serial number. The single number only allows the download, but no activation.

https://www.dictation.philips.com/ch...
The VoiceTracer speech recognition software only works together with Philips VoiceTracer audio recorders. To download the installation file, enter the serial number of your VoiceTracer and then click "Download".

No. The software is not included. And so far I can't buy it anywhere in Switzerland. Not even from Philips on the HP for download.