To enable Arabic in Photoshop CC, go to preferences (Ctrl + K) > 'Type' tab > set the text engine to MIDDLE EASTERN AND SOUTH ASIAN. Restart Photoshop. Open Photoshop again, go to the Type (in the Menu) > language options > chose MIDDLE EASTER FEATURES. (this enables the right-to-left direction in the paragraph panel).
You're all set now.
Please note that when installing Adobe CC, you must choose "ENGLISH-ARABIC" language in the installation wizard, instead of the default "English", otherwise you cannot use Arabic. If you haven't done this you must reinstall Adobe with language set to Arabic/English.You don't have to buy the "Middle Eastern Version" to be able to use Arabic (like it used to be before), now with Adobe CC all you have to do is click the (ENG-AR) language in the installation. (that's good news)
Please note that in Illustrator/InDesign, Arabic is enabled by default, but you still need to enable the (English-Arabic) language in the installation.
Good luck.
Comment if you need help.