Samsung Smart Switch Mobile can be downloaded from the Google Play Store, please follow the instructions below.
– Please reboot a phone and go to Settings → Apps → Google Play Store → Clear cache and data → Then, try to download again.
Smart Switch gives you the freedom to move your contacts, music, photos, calendar, text messages, device settings and more to your new Galaxy device. Plus, Smart Switch™ helps you find your favorite apps or suggest similar ones on Google Play™.