Installing Play Store on Chinese Samsung Note 3
Upon searching at XDA, few had success in rooting Galaxy Note 3 (Chinese version) SM-N9006 and installing Google PlayStore via CWM. Nobody there has mentioned why root is required to flash CWM via ODIN. My guess is it is required to flash CWM by ODIN. CWM is required to flash GApps. 

Please follow the instuctions in this thread at XDA where users have reported success with CWM and PlayStore functionality. 

There is another thread which uses a safe method for rooting without disturbing Knox. I would recommend trying it out before following the first link for flashing GApps. 

Disclaimer: I do not own this device and any answer provided by me is found from internet search and the rate of success may vary. Please read thoroughly before proceeding to avoid bricking your device.