Newer versions of the Hurricane Wheels Brushless Gimbal Interface Mk2 have a different RF module (for legal reasons), which is not compatible to the Ronin's internal receiver.
However, connecting an external receiver is a piece of cake:
1. Turn off your Ronin.
2. Connect the RC receiver with the supplied S-BUS cable to the PPM/DBUS port of the Ronin.
3. Turn on the Ronin.
4. In case you haven't already, turn on your Hurricane Wheels Brushless Gimbal Interface Mk2.
5. The Ronin will now be connected to the HW-BGRCI Mk2. If you want to disconnect, for example in order to use the Ronin's own RC transmitter, just turn off the Ronin, pull out the D-Bus cable and turn the Ronin back on.