If you want to use the ldap to allow developers to login into your developer portal you will need to use the Drupal LDAP module that is included in the Apigee distribution.
As a pre-requisite for this you will also need to install the php-ldap extension.
If you cannot install the php-ldap extension using "yum install php70-ldap" you will need to download the correct package from https://centos.pkgs.org/7/ius-archive-x86_64/php70u-ldap-7.0.15-1.ius.centos7.x86_64.rpm.html and install it
You may additionally need to restart the nginx process.