If it's anything like S1, it's the VST3 version that makes it available via ARA - IOW, there is no ARA "version", it's just the VST3 version that's needed.
 

I don't know- I remember something asked me about ARA version and I unchecked it. How do I get it back? It would not let me to go back and install Melodyne only in custom install mode. I have tried to open the wav, and it opened something with white background, but my original wav clip became solid yellow (no wav image) and said, "busy" as if it was loading. Suspicious!

Also "Open Editor" function is grayed out, I can "Create Region FX" if I select wav clip. But shouldn't I be able to open Editor?

You need an ARA clip selected for "Open Editor" to become available.

I cancelled Rapture install and I did get the final 
 
Read Me
Launch Application
 
dialog

What is ARA clip? When regular clip selected, it only has option for "Create Region FX". Also I have tried Custom installation and disabled everything except melodyne, so it was ready to install, but I got scared and canceled it. Shold I leave only Melodyne checked and go with installation and see if there ARA option to install? Thank you.