Thank you for asking all your questions before buying.
The more details you can provide, the better. The fewer details you provide, the longer it could take to sort out the issue. Usually we need to be able to reproduce your issue to be able to fix it, so providing screenshots of your settings, error logs, and a walk-through of what you've already tried will help a LOT. Thank you!
If your Wordpress theme is not available free-of-charge on the Internet, please share your theme files (ZIP). Otherwise, please suggest above a URL where we can download it if necessary.
Your PDF
Please share a copy of the PDF you are experiencing trouble watermarking. It helps when we can review the PDF and test ourselves. Any copies in our possession are destroyed once your issue is resolved or upon your request.
Note: Please do not send watermarked, passworded, or encrypted files if you wish for us to troubleshoot for you.
Error Log
It is also helpful to
turn on error logging in your WaterWoo settings so that you may have more information about troubles you are experiencing. Please upload a .txt or .log log file from Wordpress or WaterWoo debugging.