Failed to connect gsuit

Sir i have been trying to connect g suit with wp smtp . When i tried to authorize by clicking allow button on gmail, it is redirecting me to my site with a error message ” This page could not be found”
when i tested sending mail on Wp this is the error message found.Kindly help me to resolve this issue

Versions:
WordPress: 4.9.4
WordPress MS: No
PHP: 7.1.9
WP Mail SMTP: 1.2.5

Params:
Mailer: gmail
Constants: No
Client ID/Secret: Yes
Auth Code: No
Access Token: No

Server:
OpenSSL: Yes
PHP.allow_url_fopen: Yes
PHP.stream_socket_client(): Yes
PHP.fsockopen(): Yes
PHP.curl_version(): Yes
Apache.mod_security: No

Debug:
Error while sending via Gmail mailer: {
“error”: {
“errors”: [
{
“domain”: “global”,
“reason”: “required”,
“message”: “Login Required”,
“locationType”: “header”,
“location”: “Authorization”
}
],
“code”: 401,
“message”: “Login Required”
}
}

The page I need help with: [log in to see the link]