From the online PDF I found, it need a serial com port to connect to your computer.
The port number refer to one of those serial ports.
It's an old device made at a time when all computers had at least 2 com ports, but not all had any USB ports...
If your computer don't have any serial com port, you can't connect your organiser, or need to get a serial expantion card and install it in an unused slot into your computer and use that added serial port.
Electro
October 2012