Hello,
The 5.0 appliance / vmware image is based upon a linux kernel which means it doesn't not run windows and can be joined to a domain like the software version of the ACS. The way the remote agent worked was you installed it on a domain controller so that an ACS could speak to several domain controllers without itself being a part of that domain.
This functionality is not needed on the 5.0 because it has native LDAP support and can be integrated towards an Active Directory environment.