Take a look at the sentence again:
Although you might not believe it, Antonio actually benefits from his chicken
scratch handwriting because no one can read it,
Antonio doesn't have to worry about using the right word or the correct
spelling.
Because no one can read it is a subordinate clause, so it cannot stand alone. Antonio doesn't have to worry ... begins a main clause. When you connect a subordinate clause to the main clause that follows, you should use a comma.
Go back to the sentence to try again.