Do i have to complete this quest to continue the main story?I don't really wanna play the card game.
Unfortunately, it's mandatory now. But you can set the difficulty to the lowest level—that will make progression much easier.
i couldn't find it in the settings. where do u turn the difficulty down?
You can select the difficulty before each adventure. When you click the spot under the "Start" button, there should be a difficulty option. Though I don't remember if it's already in the public version. I think it should be.