After clearing one of the tutorials in the stream, a popup showed up about obtaining gems.
“Gem”
“A valuable jewel that emits a mysterious shine.
It is used in the shop to buy card packs and accesories.”

While the game is indeed free to play and it is expected that it will have a system based on some currency like gems, what you can do with the gems and how many you will obtain may not be final, as all the footage had a note explaining that the game is currently in development.