ROOT_DIR Error after Install (XAMPP)

after Install i get the Errors:

Warning: Use of undefined constant ROOT_DIR - assumed 'ROOT_DIR' (this will throw an Error in a future version of PHP) in C:\xampp\htdocs\!Kundenlogin2021\script\lib\classes\labels.php on line 22

Warning: require(ROOT_DIR/lib/includes/english.php): failed to open stream: No such file or directory in C:\xampp\htdocs\!Kundenlogin2021\script\lib\classes\labels.php on line 22

Fatal error: require(): Failed opening required 'ROOT_DIR/lib/includes/english.php' (include_path='C:\xampp\php\PEAR') in C:\xampp\htdocs\!Kundenlogin2021\script\lib\classes\labels.php on line 22

Apache/2.4.37 (Win32) OpenSSL/1.1.1a PHP/7.3.0 Server at localhost Port 80

also with PHP 7.2.0 tested, new installed, same error.

Any ideas?

Please use the latest version to install the PHP login script and please note in your localhost you would need php gettext module installed to make it working thanks. 

Let me know if you have any further questions.