Admin App

Hi

If your going to make the admin backend in codeigniter then thats what the modules folder is for if I'm not mistaken, use the app folder for the frontend for normal users, then create a /modules/admin, and duplicate the folder structure from the main app inside it (it has to have PSR4 namespaces), setup your app/config/autoload.php file. It's in the manual.

Failing that, use virtual hosting as has been suggested. If your using Windows I,ll walk you through it, it's fairly easy.

Hope that helps.