Sign up for a Samsung Phone account online and use it to log into the Tizen store, then download the Whatsapp Messenger from the store.
Caveats
Samsung has got this weird thing going on with sellers where you cannot be able to log into/sign into the store if your put in a sim card from an unsupported country. This is done by checking the MMC part of the sim card so you need to first put the sim card from the supported country and use WiFi to login, put the local SIM and then download the App.
