If this is a new install I'd recommend you completely remove Zimbra from the system qith the following command:
That will remove everything including any email (if you have any), after that's finished remove the /opt/zimbra directory if it still exists. If this is behind a NAT router (or firewall) the you'll need a
Split DNS set-up and a valid (and correct) /etc/hosts file - check the Quick Start Installation Guide for the format and search the forums for details on how to verify the DNS & host file are correct.
When you've done that run the install script again and when you get to the question about 'changing the domain name' answer yes then enter the correct domain name (e.g. yourdomain.com not the FQDN of your server). See how you get on with that.