I got kicked out of the tutorial dungeon because I played a class that I'm not used to playing

Yesterday, I decided to create a priest to learn how to play this class and when I got to doing the tutorial dungeon (in Exile Reach), the person who joined me in the dungeon decides to kick me out with the excuse of playing badly and being a bad DPS when we have reached the end of the dungeon.

Plus, I don't know what I did that was different than usual and the few times I was kicked out of a dungeon, I never knew the reason (maybe it's because I play badly, but at the same time, I don't play differently from all the other times when I'm not rejected from the dungeon).