接管Openresty和PHP-FPM上的项目

I have set up a Linux Server with Apache2, PHP-FPM, MariaDB.

Firstly Will Apache2 be able to successfully replace OpenResty?

The project is WordPress.

Secondly, I see a folder (php-bin) which contains register.php, login.php, profile.php, but the code inside them is incomplete, it doesn't have any include statement but uses certain undefined variables. I am sure the previous developer has some loader logic to access that code. I found out that there is a loader.php file in the public_html which's flow goes like: first verifying the url by hard-coded string comparison, then initiating the SQL DB setting variables used inside files inside php-fpm and finally calling a file from php-bin. I believe Loader.php explodes the url based on "/" and the developer uses some logic to access files inside php-bin. But I am unable to successfully call any of the files in the php-bin through Loader.php using my assumed logic flow. The server is returning an error 500. Can anyone help me with reverse-engineering this project?