Trouble setting codeigniter with plesk

Hello, I have tried creating an app with codeigniter in plesk following this post "Installing CI4 app on Plesk (codeigniter.com)" but I do not get even the index page working. I only get 500 internal server error.

Does anybody have any idea of what the problem might be?

I solved the problem, plesk had deactivated FollowSymLink, so codeigniter could not work, activating it solved the problem.