An attempt to run a third party script on Catalina is described: https://apple.stackexchange.com/q/431385/187540

Test results after executing `xattr -rd com.apple.quarantine /Users/user/Desktop/bates-label-a-pdf`:

    user@JUPITER ~ % '/Users/user/Desktop/bates-label-a-pdf/bates-label-a-pdf.app/'../bates-label-a-pdf.sh "/Users/user/Desktop/bates-label-a-pdf/Exhibits_ActivityReport.pdf"; exit
    /Users/user/Desktop/bates-label-a-pdf/bates-label-a-pdf.app/../bates-label-a-pdf.sh: line 18: /Users/user/Desktop/bates-label-a-pdf/bates-label-a-pdf.app/../pdftk/bin/pdftk: Bad CPU type in executable
    /Users/user/Desktop/bates-label-a-pdf/bates-label-a-pdf.app/../bates-label-a-pdf.sh: line 21: /Users/user/Desktop/bates-label-a-pdf/bates-label-a-pdf.app/../labeling/generate-labeling-pdf: Bad CPU type in executable
    /Users/user/Desktop/bates-label-a-pdf/bates-label-a-pdf.app/../bates-label-a-pdf.sh: line 22: /Users/user/Desktop/bates-label-a-pdf/bates-label-a-pdf.app/../pdftk/bin/pdftk: Bad CPU type in executable
    mv: /Users/user/Desktop/bates-label-a-pdf/bates-label-a-pdf.app/../labeling/labeling.pdf-compressed: No such file or directory
    /Users/user/Desktop/bates-label-a-pdf/bates-label-a-pdf.app/../bates-label-a-pdf.sh: line 26: /Users/user/Desktop/bates-label-a-pdf/bates-label-a-pdf.app/../pdftk/bin/pdftk: Bad CPU type in executable

User ***mmmmmm*** commented: [The shell scripts need to be put inside the app bundles - as well as the pdftk executable][1] and confirms that pdftk is not in the .app.

The .zip file provided by the thirty party contains `pdftk` and other `labeling` functionality:

[![enter image description here][2]][2]

 
Is the remedy a simple matter of copying

 1. foo.sh files into the respective foo.app files?
 2. copying `labeling` and `pdftk` to a location with bates-label-a-pdf.app?  Where exactly?
 3. modifying the .plist?

Contents of ***application bundle*** bates-label-a-pdf.app:
[![enter image description here][3]][3]

If yes, then an example to follow example would be appreciated. 

  [1]: https://apple.stackexchange.com/a/431400/187540
  [2]: https://i.sstatic.net/Tf3ST.png
  [3]: https://i.sstatic.net/90Gnn.png