I actually need the installation files for a system that does not have internet access. Is there somewhere I can download the actual files so I can copy them to my system?
The 9.6-3 versioning doesn't actually indicate the version of postgres that would be downloaded, but instead it corresponds to the versioning for the .repo file itself (9.6, patch version 3). After you have installed this .repo file, you can do "sudo yum install postgresql96" and it will download the latest PostgreSQL 9.6 version available from PGDG.