Acronis Files Connect (formerly ExtremeZ-IP) Print Server allows you to define a single PPD that will be downloaded to the Mac for each print queue. Some printer manufacturers may require additional software be installed to use this PPD.
PPDs are used by Macintosh computers to determine the features that are available for a specific printer. Some printer manufacturers add features to their printers that require more capabilities than the standard Macintosh OS X print drivers can provide. These features are usually implemented using what are called CUPS filters. The vendor then references these CUPS filters in the PPD so that the Mac will know that it needs to use them whenever the user attempts to print to that printer. Unfortunately if the filter has not been installed the user will not be able to print to the queue.
The solution to this problem is to install the the latest version of the third party printer drivers on the Mac client before using the a new PPD on the Acronis Files Connect print server. Rarely there could be issues if you have different versions of Mac OS X as well, as they may require different PPDs or CUPS filters.