AKINCILAR 1- I want to use this script as an image selector on my website. Just like the WordPress media manager. Is this possible?
I am not familiar with Wordpress media manager. If you mean you want to be able to "select files" from Files Gallery, and insert into Wordpress content editor on click, sorry this is not an option and not easy to implement.
AKINCILAR 2- I do not want the page to be opened by calling the URL directly. For example: I will use domain.com/admin/filemanager.php.
You may of course rename
filemanager.php, and also add a login.
AKINCILAR I want only users who are logged in to my website as admin to be able to see it. Is this possible?
Then you need to port your website's login mechanism to work with X3. It can't do this by default.
AKINCILAR 3- I want only the domain.com/images/ folder to be displayed. It will never show other folders. Is this possible?
Your can point Files Gallery root option to the images folder yes, and it won't show any other folders. It will of course show any subfolders inside the "images" folder, unless you hide them with dirs_exclude option.
I am running PHP 8.2, but I am pretty sure Files Gallery works also in PHP 8.3.