Make Website Work in Docker Image

I need a docker image where the supplied website works* (the website shows, and contact forms send). I don't have a lot of money and have tried to figure this out but no luck so far. It's currently working on another server, the website is [login to view URL], you can see it works now, but my docker image for some reason won't work despite matching php versions and everything. Any help is appreciated. I get the following error, Fatal error: Cannot redeclare external_redirect() (previously declared in /var/www/public_html/livesite/application/helpers/[login to view URL]) in /var/www/public_html/livesite/application/helpers/[login to view URL] on line 7 I did some research into the reasons for the error but it doesn't make sense since the site is working right now... The project is a code igniter project , here is download link : [login to view URL]