Cannot Find devtoolset-6

I have a desktop machine currently with RHEL 6.9 installed, currently under the "Red Hat Enterprise Linux Desktop, Self-Support" subscription.

I have additionally purchased and subscribed to "Red Hat Enterprise Linux Developer Suite", so I could gain access to the devtoolset-6 package. Furthermore, I have successfully enabled the following repositories:
- rhel-6-desktop-optional-debug-rpms
- rhel-6-desktop-optional-rpms
- rhel-6-desktop-optional-source-rpms

However 'yum search devtoolset' yields no results, and 'yum install devtoolset-6' fails with "No package devtoolset-6 available".

What am I missing to get this package?