If you subscribe to the Creative Could, open the Creative Cloud app ans click the gear icon near the upper right to change the language, then download the English/Arabic version of ID.
Peter, Tasmeem is not just the regular ME edition of InDesign. I think
it is an InDesign extension published by Winsoft, the French company who
originally developed the Middle Eastern version of InDesign before Adobe
took it over.
So the OP should probably check out the Winsoft website to see if it's
still available, and for which versions of InDesign.
@Ariel – Just checked. I think the plug in is only available for CS5 and CS5.5. Maybe a new version for CS6 or CC is under construction, but I couldn't verify this…
@Peter – "Tasmeem" functionality is needed for special Arabic calligraphy (or other things a swell).
I don't set Hebrew or Arabic, so I thought Tasmeem was a basic function included in the off-the-shelf builds, and I appreciate the clarification from both of you.