App not verified Google error

Hi,

It took me a lot of struggle to even get to this point in the setup. When the plugin attempts to “Grant permission with Google,” I get to the account selector page, click on the pertinent Google account (associated with the email address I’m using for PostSMTP setup), and I am stopped by an error message, “This app isn’t verified. This app hasn’t been verified by Google yet. Only proceed if you know and trust the developer. If you’re the developer, please submit a verification request to remove this screen.” Then I am presented with a button to go, “Back to security” or a link to “Advanced” options.

The configuration of this plugin has taken far too much time!!! Please help!!!

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