Andy,
Are you on 6.5 or 6.5.1? ESX version? The vmware guides for 6.5 and 6.5.1 are slightly different, where 6.5.1 uses a vmware proxy server for NBU intergration. This proxy is the only place you will need to install NBU software for backing up VMs.
Here's the links for the 6.5.1 guide and config: