Multiple build issues

Hi
I am trying to follow this tutorial but there have been multiple issues:
- The Firebase/AdMob pod results in two conflicting installations for both Firebase and GoogleUtilities
- (you get Firebase 3.6.0 as well as latest Firebase, and you get GoogleUtilities 1.3.2 and 7.13.0)
- This results in license errors during pod installation ("eg Unable to read the license file `LICENSE` for the spec `Firebase (9.6.0)`") and build errors when building (eg says it can't find the GoogleUtilities import)
- Some Googling suggested I swap the Firebase/AdMob pod for the Google-Mobile-Ads-SDK pod, but this resulted in various build errors because this code is using GIDSignInDelegate, which is now deprecated. I tried following the migration guide (https://developers.google.com/identity/sign-in/ios/quick-migration-guide) but I didn't understand this code well enough to be able to do this. I did manage to finally get the code to build by simply commenting out some code and changing some other bits, but once the project was finally running, I got an error "The Google Mobile Ads SDK was initialized without an application ID. Google AdMob publishers, follow instructions at https://googlemobileadssdk.page.link/admob-ios-update-plist to set a valid application ID. Google Ad Manager publishers, follow instructions at https://googlemobileadssdk.page.link/ad-manager-ios-update-plist." 0x000000010e307c40" and at this point I gave up as I really only want to follow a simple Firebase tutorial rather than address all these issues, and I know nothing about Google Ad Manager or AdMob.