I am still learning. It is my understanding that you can + or ❤ a track or album and add to your collection or playlist. But if Tidal removes it from there site it also gets eliminated from your Collection or Playlist.
I am unaware that you can actually backup a song or album and keep forever?
I think I am correct?
When Tidal removes the item (either a track or a complete album), you still have it on your collection. It appears 'lighted' on the mobile app, and you can even share/copy the link.
But, when you click on it to see it or to play it, the app says "it is not longer available" or similar error depending on the platform.
The 'download' option would be useful to play 'offline' the content when no internet connection is available. BUT this option is not useful for me as I only find it in the mobile App, and I don't use the mobile to listen Tidal music, just to look for albums and add them to 'My Collection'.
Then, I use Fire TV 4K, to listen to Tidal Atmos on my Home Theater. But the Fire TV Tidal App lacks search funcionality, No add to My Collection, and no 'download' feature, as there is not too much space to download anything, only the app cache on Fire TV, that I have to clear-up from time to time when Fire TV become slow or buggy.
I do not know if other playforms such as Apple TV or Rocku has Tidal app with those functionalities. And when a 'download' is removed from Tidal I suspect it could be played until next Internet connection on the device that would be marked as 'not available'.
If there would be other methods to rip or 'real download' Tidal content, those would not be 'legal' and I don't know if they exist yet.
Sooo.... Time to buy some more Blu-ray's ...????