Hi DD,
Samsung Z2 is powered by Tizen Operating System. Google Play Store is for Android powered devices. There RE information on the web how to install Play store on Tizen OS, you can follow it on your own discretion, but I would not recommend since there will be compatibility issues possibly on the app. I would suggest you find a mid-range phone that runs Android so you will not have compatibility issues.
I trying to open the WhatsApp installed on myZ2 but it keeps asking to download Facebook service and then freeze or stop installation