How to convert a CDT document into PDF format?

On a mac? Can't you use print as PDF?

 

If you can print it -- check to see if the pdf box is available -- print to pdf is a quick way.

If you want to control the size and quality of the file, you may have to do some file hopping and "save as" the file in a format the final pdf creation app can use.

Do you have a...

File > Publish to PDF.
Click Save.

Edit: Download a copy of the Illustrator trial (if they have one for Mac OS X) and this illcs2ip_coreltoai.pdf