Error Google account conf Raspberry pi

Hi,

I’ve configured the plugin with a gmail account. I do everything according to this guide:
https://wpmailsmtp.com/docs/how-to-set-up-the-gmail-mailer-in-wp-mail-smtp/
but at the last step when it sends the test email there’s an error:

Email Source:
Mailer: Gmail
invalid_client
Please make sure your Google Client ID and Secret in the plugin settings are valid. Save the settings and try the Authorization again.

I have the WordPress installation in a Raspberry pi 4 at home. Do I have to open any port in my router for the plugin to work?

thanks
David