How many quizzes must I create before I can create crosswords? Will I be notified or do I have to request to become an author.

I don't know exactly how many quizzes you have to have online, but if you click on "Create a Crossword Puzzle" it will tell you whether or not you are eligible to create a crossword.

http://www.funtrivia.com/crossword/crossnew.cfm