3D Issue Version 9 installer is downloaded from the internet rather than from Apple’s App Store so you need to click “Open” in order to proceed. This is similar to any other Mac applications downloaded from the internet.
Because the FlipBooks application needs to launch a secondary “HotFolder” application, a second prompt is displayed as well.
Do I need to click “Open” for both programs?
Yes.
You need to allow “Flipbooks” in order for the main application to launch. You need to allow “Hotfolder” to enable the conversion process. If you accidentally click “Cancel”, a the prompt should appear again shortly after importing your PDF file into the FlipBooks application.