I am interested in the answer to this too!
Jeez, I wish that Adobe would clean up its documentation. If you go into your Creative Cloud preferences, you can change your default language to English (Arabic) or English (Hebrew). Then, if you uninstall InDesign and re-download, you'll get the ME edition instead of the plain-vanilla Latin-script English version. Menus will still be in English, but you'll get all of those RTL formatting tools necessary for Arabic/Hebrew/Persian/etc.
PERFECT ! thanks, I had been using Intools plugin but now I have the ME tools by doing as you said, i didnt even uninstall first - i just changed language in preferences and installed again !
How can I change my Arabic version of InDesign to English? I've installed the Free Trial so cannot uninstall. Everything is currently set to Arabic. Any help would be much appreciated.