This is a lot of game to design and make work in just seven days! I'm really impressed. I love hidden role games and I am looking forward to your improvements!
I think what would improve this game the most aside from a tutorial is make the cards a bit easier to stack, and more clarity between types. I'd increase the hitbox size so it's easier to drag one card on top of another, and add a highlight effect to the card you're stacking on top of so the player has a visual feedback for when they can release a card and it will place. I had a hard time telling the card types apart until I noticed the tasks had a progress bar at the top. I'd probably make people have one background color and the tasks a different background color to start.
Amazing job!