Collect the details from the actual set
Record the model code, software version, store region and whether the display is a television or is showing an external HDMI player. Search the TV store by the full app name. If the store shows several close matches, compare the publisher and help destination before entering any account details.
If the app is missing
Look up the TV model's supported installation options in Samsung support. A dedicated streaming device is a separate installation path if a compatible app exists for it. Check that device's store and your account's login format before spending money on hardware.