Hi,
I’ve just resolved the same issue on another website, and the reason was:
Google Analytics Data API has not been used in project 623857236848 before or it is disabled. Enable it by visiting https://console.developers.google.com/apis/api/analyticsdata.googleapis.com/overview?project=623857236848 then retry. If you enabled this API recently, wait a few minutes for the action to propagate to our systems and retry.
You can check if this API is enabled for the credentials you created in the Google API Console, maybe this is also a reason.
I believe this will be useful to you.