React Gatsby Help

I recently download a react-gatsby project.
I couldn't run the project.
-https://github.com/EmaSuriano/gatsby-starter-event-calendar

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Error: AssertionError [ERR_ASSERTION]: Please add the value for CLIENT_EMAIL in your environment variables.

I think there are some env values like "PRIVATE_KEY", "PRIVATE_KEY_ID", "PROJECT_ID"...

Please Help Me...