Serious problem with sending validation messages

Hello everyone, I have a serious problem with sending validation messages to users, these are not being sent, install different “SMTP” plugins that reconfigure the PHP function wp_mail () so that an appropriate SMTP provider is used, but none of them worked for me, the last one I installed was “WP Mail SMTP” create an account in Google Developers and configure the application with the data requested, return to “GMAIL SMTP” the data requested, validate the permissions and I get this message:

“This app was not verified
Google has not yet verified this app. Continue only if you know the programmer and it is trusted.

If you are the programmer, send a verification request to remove this screen. More information

Advanced configuration”

I’m stuck at this point because my users do not have access to the important features of my website, but can enter or register in it and for this they need to be notified through their mail.

I greatly appreciate who can help me
I remain attentive to your response, have an excellent day.