Problem notarizing app created with pyinstaller

[Paul Fishback]

I have a very simple app, "determinant_calculator.app" created using Python 3.9 and pyinstaller. It functions fine on my own Mac and I want to get it notarized. I have an Apple Developer's license but have no experience using it yet nor have I used Xcode. 

I've tried following the directions at https://github.com/pyinstaller/pyinstaller/wiki/Recipe-OSX-Code-Signing. 

I first went to the Apple Developer's website and created a certificate, developerID_application.cer, which I downloaded to my desktop. Within Keychain Access, I uploaded the certificate and see it under "My Certificates" as "Developer ID Application: PaulF (47A67S7RBW)"

The bundle contents of determinant_calculator.app  include info.plist, which contains the lines

<key>CFBundleIdentifier</key> 

 <string>org.pythonmac.unspecified.determinant_calculator</string> 

 <key>CFBundleName</key> 

 <string>determinant_calculator</string>

At the command line I then typed

codesign -s "PaulF" determinant_calculator.app

It seemed to work okay. I typed it again and was told the app was already signed.

I zipped the file and shared it with another computer using Dropbox. The other computer could not open the decompressed file because it came from an "unverified developer."

What fundamental part of this process am I missing? Can I complete the notarization process without using XCode?

Thanks

Paul