Hello, the Samsung Galaxy Z2 (and other Tizen models) run Tizen OS, and as such does not run on Android. This means that you are limited to the Tizen store for downloading apps. It is not possible to download the Google Play Store for a Tizen phone.
Tizen was designed by Samsung in an attempt to reduce their reliance on Google's Android OS. The Tizen Store is like the google play store, however it is specifically designed for Tizen apps.