Warning: require(vendor/autoload.php): Failed to open stream: No such file or directory in /export/vol2/httpd/htdocs/academic/vetmed/FedEx/PHPMailer-master/get_oauth_token.php on line 18

Fatal error: Uncaught Error: Failed opening required 'vendor/autoload.php' (include_path='.:/php/includes:/export/vol2/httpd/htdocs/includes:/export/vol2/httpd/htdocs/its/oit/includes ') in /export/vol2/httpd/htdocs/academic/vetmed/FedEx/PHPMailer-master/get_oauth_token.php:18
Stack trace:
#0 {main}
  thrown in /export/vol2/httpd/htdocs/academic/vetmed/FedEx/PHPMailer-master/get_oauth_token.php on line 18