For your information, I have also the same problem. Here is the error message “Formidable PRO2PDF: Folder /home/lapataubone/web/kampuslapataubone.ac.id/public_html//tmp/ should be writable. Please change its permissions to 777. Can not open a temporary file for writing, verify the permissions.”
I created a TEMP folder under public_html (WP root) and set permission to 777 but it does not solve the problem.
Instead, I created a TMP folder (Not TEMP folder) under public_html and set permission to 777 and it solved mu problem.
Thank you