The ULTITUBE PRO comes with a D5 NEXT pump, which has its own RGBpx port, and a 50 cm RGBpx cable.
You connect one end of the RGBpx cable to the RGBpx port of the D5 NEXT, and the other end to the 'IN' port on the RGB LED ring.
The included 50 cm RGBpx cable may be a bit long, but there are
other cable lengths available.
Don't know if the 4 cm one would be long enough, if not, the 10 cm should work.
Edit: the D5 NEXT's RGBpx port may be assigned as the aquabus port, mutually exclusive. For your application you want it to be RGBpx.
The two RGBpx ports on the OCTO can be used for additional lighting in the case.