Basic API question

I ran Google WordPress on a site for quite awhile. One of the things it did was list events from a google calendar. That site is down, at least for the foreseeable future–not enough volunteers to maintain it. I’d like to display the calendar on a different site (on this page: https://www.dewritersstudio.org/calendar/de-literary-events-calendar/ ).

When I go to deal with the Google api code, I see that api is already active for Google calendar, which makes sense. Since I’m dealing with the same calendar that was on the old site, it seems like I should use the existing api rather than create a new one. But I cannot for the life of me find that api–not on the old website and not in the google developers’ area. Can anyone tell me where to look for that api code? Or do I have to create a new one even though it’s the same calendar? I have to deal with api codes so seldom that I can never remember how they work.

The page I need help with: [log in to see the link]