The Configuration menu proceeds as follows.
1 . To set API information and Administrator SMTP mail server information, you must verify the domain. Clicking on the 'Verify Domain' button in the pop-up window will take you to the domain verification page. After verifying domain, the pop-up no longer appears when the administrator API key is registered.
2. Enter the Admin API Key and API token. If you don't have Admin API Key or API Token yet, click 'Admin API Key' / 'API Token Creation and Management' button at the bottom to go to the creation page.
3. In the SMTP Mail Server menu, enter your email and password. You can authenticate it with G Suite or Google account.
If you need help registering Admin API Key / API Token / SMTP Mail Server information, please refer to the help link(see screen shot below) on the right.
