Warning: require(vendor/autoload.php): failed to open stream: No such file or directory in C:\wamp64\www\gmwindows\PHPMailer\get_oauth_token.php on line 59

Fatal error: require(): Failed opening required 'vendor/autoload.php' (include_path='.;C:\php\pear') in C:\wamp64\www\gmwindows\PHPMailer\get_oauth_token.php on line 59