/admin/ says file does not exist, but it does.

Warning: require_once(/customers/3/e/0/bekerhuislambregts.nl/httpd.www/system/startup.php): failed to open stream: No such file or directory in C:\xampp\htdocs\customers\3\e\0\bekerhuislambregts.nl\httpd.www\admin\index.php on line 21

Fatal error: require_once(): Failed opening required '/customers/3/e/0/bekerhuislambregts.nl/httpd.www/system/startup.php' (include_path='C:\xampp\php\PEAR') in C:\xampp\htdocs\customers\3\e\0\bekerhuislambregts.nl\httpd.www\admin\index.php on line 21

<?php
// HTTP
define('HTTP_SERVER', 'http://REDACTED/customers/3/e/0/bhl.nl/httpd.www/admin/');
define('HTTP_CATALOG', 'http://REDACTED/customers/3/e/0/bhl.nl/httpd.www/shop/');

// HTTPS
define('HTTPS_SERVER', 'http://REDACTED/customers/3/e/0/bhl.nl/httpd.www/admin/');
define('HTTPS_CATALOG', 'http://REDACTED/customers/3/e/0/bhl.nl/httpd.www/');

// DIR
define('DIR_APPLICATION', '/customers/3/e/0/bhl.nl/httpd.www/admin/');
define('DIR_SYSTEM', '/customers/3/e/0/bhl.nl/httpd.www/system/');
define('DIR_IMAGE', '/customers/3/e/0/bhl.nl/httpd.www/image/');
define('DIR_STORAGE', '/customers/3/e/0/bhl.nl/httpd.www/storage/');
define('DIR_CATALOG', '/customers/3/e/0/bhl.nl/httpd.www/catalog/');
define('DIR_LANGUAGE', DIR_APPLICATION . 'language/');
define('DIR_TEMPLATE', DIR_APPLICATION . 'view/template/');
define('DIR_CONFIG', DIR_SYSTEM . 'config/');
define('DIR_CACHE', DIR_STORAGE . 'cache/');
define('DIR_DOWNLOAD', DIR_STORAGE . 'download/');
define('DIR_LOGS', DIR_STORAGE . 'logs/');
define('DIR_MODIFICATION', DIR_STORAGE . 'modification/');
define('DIR_SESSION', DIR_STORAGE . 'session/');
define('DIR_UPLOAD', DIR_STORAGE . 'upload/');

// DB
define('DB_DRIVER', 'mysqli');
define('DB_HOSTNAME', 'REDACTED');
define('DB_USERNAME', 'bhl');
define('DB_PASSWORD', 'REDACTED');
define('DB_DATABASE', 'bhl');
define('DB_PORT', '3306');
define('DB_PREFIX', 'bhl_');

// OpenCart API
define('OPENCART_SERVER', 'https://www.opencart.com/');