It seems that you tried to move your website’s source code outside of the htdocs folder of your site. That’s not going to work, because our PHP installations are restricted to only allow access to files within the htdocs folder of that specific website.
If you want to setup a website that normally has the publicly accessible files in a subfolder, you’ll still need to upload all your website files to the htdocs folder. After that, you can use .htaccess rules to restrict access to the root folder and direct requests to the public folder.