The logic in ros2/ci has two options to use Connext:

  • either install the Debian package available (which implies accepting the embedded license) or install Connext on macOS / Windows machines
  • or build Connext from source (that is what the osrf/rticonnextdds-src repo is for). Since this repo is private you would need to talk to RTI if you want access to their sources in a similar way.

Sticking to just the first option is probably fine for you.