Welcome to the forums,
Zimbra has it's own custom ldap that get's installed.
You will have to use the OpenSource edition as there's no Network Edition version for Fedora4.
(unless you want to attempt using the RHEL builds-something like:
Platform Specific - ZimbraWiki)
Have you read through the quick-start guide?:
/community/documentation.html
The place to start for migration examples:
User Migration - ZimbraWiki
(also look up zmprov & bulk provisioning)