PDF Reader Pro requires your authorization to access and open your files. Therefore, you need to allow PDF Reader Pro to get files and folders permissions at first.
While signing, you may encounter a situation where you cannot save your files, which is most likely because that PDF Reader Pro is not authorized by your file and folder.
This authorization requirement comes with the Mac system. For more information of Mac system file and folder authorization operations, please refer to the following links:
1. Control access to files and folders on Mac
2. Add apps to "Files and Folders" permissions?
Any other questions, welcome to contact us via [email protected].