Jan, the output for PDF should always create a zip file with all the patterns inside of it. We need to get this fixed, if there is a problem on our end.
Are you not always getting a zip file? Are there any errors displaying on the screen?
When you say the zip won't open, what exactly does it say? Are you using a PC or laptop? Which browser are you using?
Which pattern number is causing this problem or is it a variety of them?
Thanks for the help to get this fixed.