If you dreamed you were an author, then its dream interpretation can be that you have stories to tell. You have narrative skills and you’re good at story telling. This dream can be a hint to you, to make use of your story telling skills.
If you dreamed you were an author and you have written a fantastic fiction, this dream interpretation can be that you have created a fantasy of make-believe, in your waking life. You should be cautious about how you might ease yourself out of this situation. A house of cards is always in danger of coming crashing down.