Grant Permission with Google get Forbidden result

I think I have setup the OAuth access for Google correctly, though the steps in:

https://www.cloudways.com/blog/post-smtp-mailer-fork-of-wordpress-postman-smtp-plugin/?id=339490#step8

seem out of date. When I attempt to Grant Permission with Google, after logging into my Gsuite account I get this error:

Forbidden
You don’t have permission to access /wp-admin/options-general.php on this server.
Additionally, a 403 Forbidden error was encountered while trying to use an ErrorDocument to handle the request.

Bluehost is my host.

Thanks in advance for your help.