Hi, there!

Sorry for the late reply. I've been out of the office all last week. I'm posting my configuration LocalSettings.php. I have edited it for privacy reasons, but I think you'll get the point quickly by taking a look at it. You will note that OU, CN and other words appear there sometimes in capital letters or not. I believe that is unrelevant for your config to work as expected. What you have to make sure about is that the names your LDAP/AD entries match the ones of your config. Let's say you have a group in your LDAP called Users, then write Users in your config. Check out the groupsync and authorization parameters. I think they're related and must be both declared in order to make Authorization work properly.

# End of automatically generated settings.
# Add more configuration options below.

# LDAP
wfLoadExtensions( [
        'PluggableAuth',
        'LDAPProvider',
        'LDAPAuthentication2',
        'LDAPAuthorization',
        'Auth_remoteuser',
        'LDAPGroups'
] );

# I DON'T KNOW WHAT THIS DOES, BUT I THINK IT IS NEEDED ;-)
$wgAuthRemoteuserUserNameReplaceFilter = [
    '@DOMAIN.MY$' => '' // mod_krb5 and .htaccess
];

$wgGroupPermissions['*']['createaccount'] = false;
$wgGroupPermissions['*']['autocreateaccount'] = true;

$LDAPAuthentication2UsernameNormalizer = 'strtolower';
$LDAPAuthentication2AllowLocalLogin = true;

$LDAPProviderDomainConfigProvider = function() {
        $config = [
                'mydomain' => [
                        'connection' => [
                                "server" => "your_server_IP_or_dns_name_without_http_https_or_whatever",
                                "user" => "CN=XXXXXX,OU=Users,OU=XXXXXX,DC=XXXXXX,",
                                "pass" => 'XXXXXXXXXXXXXXXXXXXXXX',
                                "port" => Better to use 389 to avoid SSL problems just for testing, then use 636,
                                "enctype" => 'ssl',
                                "options" => [
                                        "LDAP_OPT_DEREF" => 1
                                ],
                                "basedn" => "ou=XXXXXX,dc=XXXXXX",
                                "groupbasedn" => "ou=Groups,ou=XXXXXXXX,ou=XXXXXXXXXXX",
                                "userbasedn" => "ou=XXXXXXXXXX,dc=XXXXXXXXX",
                                "searchattribute" => "samaccountname",
                                "usernameattribute" => "samaccountname",
                                "realnameattribute" => "cn",
                                "emailattribute" => "mail",
                                "grouprequest" => "MediaWiki\\Extension\\LDAPProvider\\UserGroupsRequest\\GroupMember::factory"
                        ],
                        'groupsync' =>
                        [
                                "mechanism" => "mappedgroups",
                                "mapping" =>
                                [
                                        "read" => "cn=XXXXXXXXXXXXXXX,ou=XXXXXXXXXXXXXXX,ou=XXXXXXXXXXXXXXX",
                                        "write" => "cn=XXXXXXXXXXXXXXX,ou=XXXXXXXXXXXXXXX,ou=XXXXXXXXXXXXXXX"
                                ]
                        ],
                        'authorization' =>
                        [
                                "rules" =>
                                [
                                        "groups" =>
                                        [
                                                "required" =>
                                                [
                                                        "cn=XXXXXXXXXXXXXXX,ou=XXXXXXXXXXXXXXX,ou=XXXXXXXXXXXXXXX"
                                                ]
                                        ]
                                ]
                        ],
                        'userinfo' => [
                                "attributes-map" => [
                                        "realname" => "cn"
                                ]
                        ]
                ]
        ];

        return new \MediaWiki\Extension\LDAPProvider\DomainConfigProvider\InlinePHPArray( $config );
};

# This will show errors in your browser if there are any of them (like a --verbose option I think). Remove it in production or set it to false
$wgShowExceptionDetails = true;