I bought my Samsung Smart TV a few weeks ago. I've spent days now trying to find the app but with no luck. I even tried downloading it from the web browser. The Tizen app doesn't exist either. I don't want to use Pandora when I pay for Spotify every month.
As the buyer of a Samsung UHD "Smart" TV, I had the impression those guys knew what the word "SMART" was all about. But this assumption appears to be totally wrong. In the eyes of tv-makers smart means: it can connect to the internet. Mostly through a limited number of apps that are often: 1) user unfriendly (i.e. no support for a wireless keyboard) 2) not regularly updated 3) or not at all available if you have chosen a manufacturer (like Samsung...) that is not supporting developers to develop for their platform (=Tizen).
Sony is maybe one of the few that has picked the Android OS for their tv sets. So many apps are already available for these tv's.
I no longer wanted to wait for the Samsung boys to get their act together and bought a media player of the latest generation. For some $/€ 50-60 you can buy a very powerful box that streams all (well almost all..) content in the world to your living room. Kodi + add-ons installed on a fast processor on an Android box makes your TV set really smart. Also your old model!