Attempting to publish to iOS. "Assets.car" required warning

I am an amateur Animate user. I have published my .fla to the Google Play Store successfully. I am trying to publish my Animate file to the Apple App Store without having to hire a freelance professional (though at this point frankly I would).  I'm using Animate 2020 and have downloaded and attached latest SDK from Harmon.  I have also attached certificates and provisioning profiles and icons.  I get a warning/block when I try to publish: "Warning:Assets.car is required for target ipa-app-store."  I have tried to review other posts in the Animate forum on this issue.  Adobe Support sent me a link to "AIR Native Extension Tutorials".  I followed Method 3 because it had screenshots.  Per that tutorial I opened a new project in Xcode11.4.4.1 and I imported the required images and had a 'successful' build. However I cannot find my Assets.car. I believe I am supposed to copy my Assets.car and import back in by Adobe Animate file in the publish setting in "Included files."

p.s. That Air Native Extension tutorial also has a Method 2.  That method has the final step:"Run the createAssetCar script. This will create a build directory and run the following command to build the Assets.car file: (and then some text is listed).  I would also be open to trying that method but I don't know how.

Thank you!