Web Development Issues

Not sure if this is the right place but I'm new to Linux and really liking it but having trouble setting up a web development. I have installed Apache2, MySQL and PHP7. The localhost is working as this will show my apache2 page saying it working. Mysql is working and also PHP is working. I have tested this by creating a test.php and also a phpinfo in the var/www/html folder.

Everything fine so far but my issue is when i try to use ready made CMS like Joomla, its in the right folder, but its a blank page, the same goes for another Drupal, just a blank page. What am i doing wrong?

I've Google and found no answer.