Hello! Thanks for reaching out! Even though you are during the evaluation period for Connect, you actually have access to our professional support team! If you want to shoot us a support ticket at support@rstudio.com , we can help through that avenue!
Note that when you are setting up email delivery, it is common to set it up through something other than a gmail address (enterprise SMTP server, mail sending service, etc.). In any case, if you can share the log file from /var/log/rstudio-connect.log, that may provide some helpful insight on why this is not working!
Looking through the article here, I suspect that SSL will be required to get this working, if you do want to go ahead with using gmail to route messages: https://www.lifewire.com/what-are-the-gmail-smtp-settings-1170854