Dreaming of an audition means you are trying to win the approval of your peers. You are scared of the impressions that you may give them through your day to day interactions. Are you going to sweat through the audition or ace the audition in your dreams will indicate whether you have won their approval.
Dreaming of a mask mean you want to act in ways that you currently cannot because of your concerns about people judging you. With a mask, you can be anyone you want without the fear of being known or giving off bad impressions. The truth is that everyone wears a mask every day for different situations. A group of friends will always know you differently from a group of colleagues.