I'm assuming you've pirated it
As far as I know, DLC can be downloaded if you tap on the SNES controller in the bottom screen
There you'll see a game list. Tap on birthright and tap the DLC thingy
That includes conquest and revelations
Also the maps
You'll start downloading the DLC
Enjoy
I didn't pirate the game. It's a legit physical copy. I support the developers by buying the game but I don't think DLC should ever be paid for. For the sole reason of I already purchased the game so why should I have to spend more money to unlock the full version of a game I had already purchased once. Is this process you mentioned any different now that you know I have the legit game?