Where to find the Physics DCC plugin to create Apex files?

To be able to create Apex files, you will need to install the Nvidia Physics DCC plugin from Physics SDK 3.4 (or older version)

(as of 2017, July 10th) You need to create an account on Nvidia developer zone https://developer.nvidia.com/

Then visit this URL to find the package directly: https://developer.nvidia.com/gameworksdownload#?tx=$physx_sdk,3.4.0

Note that Nvidia does not provide a package for Linux, so unfortunately, you will not be able to create Apex files from a Linux workstation