If you want to transfer files to your PC/Mac, please connect your iOS device with your computer.
1. Launch iTunes on your computer.
2. Connect your iOS device to the computer via USB cable.
3. Scroll down to File Sharing section.
3. Then find the PDF Reader app in the "Apps" tab. Tap the app icon, and you will see all the documents stored in this app.
4. Then tap the target file and tap "Save" to export the file to your computer. Or you can tap "Add" to import files from your PC/Mac to PDF Reader app.