1) When try to enable LDAP authentication on 2.0.4 on CentOS without php-ldap package it show error:

Probably php-ldap module is missing. [CUser.ldapLogin]

When try to enable LDAP authentication on 2.0.5 on CentOS without php-ldap package it shows nothing - just grey screen bottom of zabbix top menu bar.
Some error checking was broken.

2) [CLOSED] Strange behavior with LDAP authentication config:
when configured
host: ldaps://<domain controller>
port: 636
and press Test - show "Unable to bind to server"
But when configured
host: ldap://<domain controller>
port: 636
and press Test - all good.
Not cleary, its secure conection or not?

3) [CLOSED] Not clearly for what use foreign user BindDN. I developed some applications on PHP for internal use, and also used ldap authentication.
And always use only entered user/password for directly authentication.
Foreign user BindDN is not needed for authentication! Need only domain name. Example below

$dc = ldap_connect('ldaps://mydomaincontroller',636) or exit("error ldap_connect");
ldap_set_option($dc, LDAP_OPT_PROTOCOL_VERSION, 3);
ldap_set_option($dc, LDAP_OPT_REFERRALS, 0);
$res = ldap_bind($dc,$_POST['username'].'@mydomain.com',$_POST['password']); 
if ($res == true)
{ /* auth correct */ }
else
{ /* incorrect */ }