Tick anything you already have, in any order. Quests unlock once this is done.
Jung for MBTI, the Big Five papers for the empirical side. The free quizzes are the shallowest part of this and the theory is where it gets interesting.
Find the source material2 things left above. Quests are real things you go and do, so they only make sense once you have what you need.
First one waiting: Take a free personality test