Use CI4 session to protect ckfinder file manage

Hello please i am trying to use ckfinder with Codeigniter 4. I dont any way i can use the ci_session to portect the ckfinder please

Code:

$config['authentication'] = function () {

session_start();
if($_SESSION['isAdmin'])
{
    return true;
}
else
{
    return false;
}

};

The cofig file is to protect a direct access to the file manage and uses session to protected. I have try to access the codeigniter session outside it app folder but could not find any solution to this.