TYPO3 Core

followed the following snippet to create a simple bootstrap file : https://docs.typo3.org/typo3cms/CoreApiReference/ApiOverview/Bootstrapping/Index.html

when placing all the content in file i get fatal error:

Fatal error: Uncaught Error: Class 'TYPO3\CMS\Core\Core\ApplicationContext' not found in /home/simcoion/domains/simco-ion.nl/typo3_src-7.6.15/typo3/sysext/core/Classes/Core/Bootstrap.php:90 Stack trace: #0 /home/simcoion/domains/simco-ion.nl/typo3_src-7.6.15/typo3/sysext/core/Classes/Core/Bootstrap.php(118): TYPO3\CMS\Core\Core\Bootstrap->__construct('Production') #1 /home/simcoion/domains/simco-ion.nl/public_html/test1.php(6): TYPO3\CMS\Core\Core\Bootstrap::getInstance() #2 {main} thrown in /home/simcoion/domains/simco-ion.nl/typo3_src-7.6.15/typo3/sysext/core/Classes/Core/Bootstrap.php on line 90

file is in public_html directory includes typo3/sysext/core/Classes/Core/Bootstrap.php

typo3 dir is a symlink

the url to file is : http://www.simco-ion.nl/test1.php