If you are getting the error about a new event setup that means that your custom domain isn't fully setup.

If you have not started the domain setup process you can begin that here:

If you have already created your domain we would recommend following the steps in this article. Paying special attention to adding an add account and Step 3

If you need additional help we have domain set up calls available where we can help you set up the domain in your Facebook business manager.

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