How can I use my google account with Apple Calendar on OS X 10.13?

I found this but I don't have the technical knowledge to implement the last part:

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• As of August 2023, this is no longer working for syncing Contacts and Calendar, but it is working for Email, which is what really matters. I've transferred my personal Contacts and Calendars to use an iCloud account instead. This still works from OS X 10.9. – 
• Wowfunhappy
•  Aug 30, 2023 at 16:44
• In addition, I recently started a new job that uses Google Workspace, and I wanted to sync email and calendars. I created an app-specific password, but for some reason this did not work in System Preferences when I tried to add it as a Google account. However, when I selected "Add Other Account" → "Add a Mail account", I was able to add my email with the same credentials.– 
• Wowfunhappy
•  Aug 30, 2023 at 16:46
• That just left syncing the Workspace Google Calendar. I got it working, but I did have to use OAuth Hopper. It was tricky to set up and I don't understand what I did well enough to precisely document the process. What I will say is (1) you need to set up an OAuth Client ID in console.cloud.google.com, and (2) GPT4 was very helpful in figuring this out. I fed it OAUTH Hopper's readme and then asked for more specific details. – 
• Wowfunhappy
•  Aug 30, 2023 at 16:50

Thank you but to get google mail working in this scenario, it has to be setup as a 'mail' account rather than a 'google' account which means there is no calendar option. If I try and sent it up as a 'google' account (ie so I have the calendar option as well as the email one) I get the following error message:

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