Test Email Does Not work

I recently discovered my contact form on my website does not work. I installed and configured the Gmail SMTP plugin. I believe it is configured correctly. My host provider opened the TLS port. However, a test email still results in an error message indicating “bad credentials” and invalid username/password, even though I am using an API. I set up credentials on Google console. Can someone help me troubleshoot this? Here is the error message when I try to send a test email:

SMTP Error: Could not authenticate.
2018-10-21 22:36:19 CLIENT -> SERVER: QUIT
2018-10-21 22:36:19 SMTP -> get_lines(): $data is “”
2018-10-21 22:36:19 SMTP -> get_lines(): $str is “535-5.7.8 Username and Password not accepted. Learn more at”
2018-10-21 22:36:19 SMTP -> get_lines(): $data is “535-5.7.8 Username and Password not accepted. Learn more at”
2018-10-21 22:36:19 SMTP -> get_lines(): $str is “535 5.7.8 https://support.google.com/mail/?p=BadCredentials c21-v6sm47735972pfe.93 – gsmtp”
2018-10-21 22:36:19 SERVER -> CLIENT: 535-5.7.8 Username and Password not accepted. Learn more at535 5.7.8 https://support.google.com/mail/?p=BadCredentials c21-v6sm47735972pfe.93 – gsmtp
2018-10-21 22:36:19 SMTP ERROR: QUIT command failed: 535-5.7.8 Username and Password not accepted. Learn more at535 5.7.8 https://support.google.com/mail/?p=BadCredentials c21-v6sm47735972pfe.93 – gsmtp
2018-10-21 22:36:19 Connection: closed
SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting

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