Ok, so the issue is here, your server says that the document root is
[DOCUMENT_ROOT] => /var/chroot/home/content/75/11465975/html which is wrong since you have installed mailwizz in a folder called mails in the html folder, so the correct value should be
[DOCUMENT_ROOT] => /var/chroot/home/content/75/11465975/html/mails
You have two ways to go about this:
1. You contact your host for advice
2. You open the file apps/init.php and at line 17 you have:
PHP:
// set the developer ip addresses, separated by a comma
defined('MW_DEVELOPERS_IPS') or define('MW_DEVELOPERS_IPS', '');
Before that line you will have to add some code, like shown bellow:
PHP:
if (isset($_SERVER['REAL_DOCUMENT_ROOT'])) {
$_SERVER['DOCUMENT_ROOT'] = $_SERVER['REAL_DOCUMENT_ROOT'];
}
// set the developer ip addresses, separated by a comma
defined('MW_DEVELOPERS_IPS') or define('MW_DEVELOPERS_IPS', '');
Then save the file and reload your backend.
However, i really advice you to have a talk with your host about this
because the way it looks right now it's not correct.