Beginning "Story" Chapter is too painful for beginners
I recently started an alt on a different device and there are a few problems.
The original intro is better than it used to be but after the last kiora fight you are _locked_ into Story Chapter 1 and cannot do anything else at all.
You have hardly any choice in your deck.
This is a _bad_ experience that doesn't represent the normal game.
Things that would help:
When you lose a game give them a green card/booster that might help and take them to the deck editing screen to help them adjust things, this part of the game needs promoting too.
Also, open up the "Training" part of the missions for play at this point too, They are safe for people to play around with and they reward cards that might help.get through the first story bit.
Otherwise this might be a _hard_ wall blocking people and making them give up in frustration.