Hello Toni,
PDFDriverInit will fail only if the user doesn't have administrative rights, this is absolutely normal because under Windows 2000, NT, XP only administrators can install a printer on the system, so if a user (not administrator) is logging to the system he / she will not be able to install any printer including our printer.  All what PDFDriverInit does is installing a printer so it will fail.
Our Delphi techincal note tn07 uses both TCDIntfEx (CDIntf210.dll) and TPDFCreactiveX (PDF Creator control). Maybe you are downloading an older version of tn07.
I didn't really get what you mean by:
On some of our PC PDFDriverInit creates a new printer (which I can select in other programmes e.g. MS-Word). But it's impossible to call the options of this new PDF-printer (neither in Word nor in our product). 
Concerning installing the PDF Printer on users machines, there are many ways to do so other than running Install.exe on each machine, you can write a small script and include it in the installation process of your application.  This script will call PDFDriverInit and then DriverInit to install the printer and keep it there.
To help you using the PDF Converter and deploying it on your users machines, please send us an e-mail to 
support@amyuni.com and we will send you the needed information that would help you.
I am sure this will help and you will be able to use and deploy the PDF Converter very easily from Delphi.
Thanks.