Hi Damin,
In all cases we've seen, this occurs from either not extracting the files properly, or the package being corrupt.
I would recommend the following:
1. Make sure you're going to a terminal session and running the following command to extract the package: tar -xvf
2. Retry the install after using that method of extracting the files. If this is still occurring, then download the Mac agent from the following location and retry:
http://support.veritas.com/docs/285821
This is actually the link for the RALUS agent and the steps to get it from our FileConnect site, but the Mac agent is in the same packaged file.
Thanks.