Rooted, really liked the box.
Since you have the sources all you had to do was understand the code and go through it step by step.
User
On VIP you didn’t get spoilers just by visiting however on Free its a total different story. If you really want to learn something ignore what others did in the browsable sites and analyze the PHP, THEN do what you think is right.
It takes three steps to user, one forward, one backward and one forward again.
Get shell, take information back, get shell again.
Take the functions used, look them up in the docs/w3schools and run them online. If you are unsure how one initial variable is declared, a certain easy-to-discover page will tell you. Make your own $name variable and run it through function after function just like the website does it.
After each function write down the output, take it to the next function and repeat.
If you want to get fancy, take the files and make your own server locally.
PHP Boolean False = 0
PHP Boolean True = 1
Root
Basic enumeration, you can run the well known script or if you do the most important things manually you will discover it pretty fast too.
If you found it you aren’t far away, run it and dont space out, focus on task ahead