Not a MODX question.
I believe you need to upgrade to Cubase Pro 10 for the ARA-Support required. But you should really contact either Celemony or Steinberg (not really a MODX question). Let us know when you find out.
I downloaded MELODYNE ESSENTIAL demo and it seems to be working perfectly in CUBASE AI.
Will play around with ESSENTIAL for about a week to make sure it is working properly with CUBASE AI.
I contacted STIENBERG and I am waiting for a response back.
As soon as they give me the lowdown I will post back here, as this info may help others.