If you have already done the below then ignore, posting this to help other users wanting to integrate Google stuff in their apps.
Regarding anything google, you have to firstly have a registered Gmail account, then the best way to approach it is go here and register for free.
Google Cloud Console
Once done, you can create a free app/project and link it to maps, search, Gmail, and loads of other google cloud services. After you are happy with the services linked then you can generate permanent API access tokens and google OAUTH key with consent screen.
There is no development for the basic linkage. Its all click and form filling to proceed.
Once done then you can do verification with Google and once the verification is done, takes a couple of days.
Your keys will have full authenticated access to all the linked services and their API's through your WordPress.
When you have all of these keys, adding any google features to your app will work with full feature functionality. Most of the plugins require these keys for the features to work. Else you will be stuck with client ICS down loading and having to import manually to update calendars.
Resources you will need to complete the process are, Access to a registered Domain and its DNS, access to the registered domains registrant email account or help from the person who owns the domain. Colour photo of your self holding ID. If registered as a business you will also need to provide company registration proof and proof of address.
The above process is vey similar for
Microsoft 365 Azure (Outlook and all the 365 could apps and services) and
Facebook & Instagram.
Hope this helps.
Jay
