Have you gone through the requirements here to be sure it meets the specs...

right side of this page   https://developers.oxwall.com/hosting

Have you checked all your default folder permissions as it says here

https://developers.oxwall.com/forum/topic/8266

recursive means every file and all subfolders and files

What is your server setup?   apache, centOS, cPanel ??? 

What version of PHP are you running?

How do you serve up your php files, using apache or something else (Server API)?

Have you run a phpinfo() to see what you have under the hood?

Does your server support FollowSymLinks ?