I'm not sure which guide you are following to set this up but based on the error sounds like the issue could be related to firewall settings, wifi security settings (try using a different wifi), a missing port setting (port 587), or you might be using an unsupported encryption protocol.
The message means that the mail server is not responding in an appropriate manner. It could be because of a network issue between your web server and the SMTP server, you could be using the wrong settings, wrong ssl setting, port, credentials, or wifi. You should confirm that you are matching the correct settings for the SMTP server you are trying to connect to.
See the related troubleshooting:
If the information helped you, please Accept the answer. This will help us as well as others in the community who may be researching similar questions. Otherwise please let us know if you have further questions and provide more details about your configuration.