If you are auditioning for a major singing role, you might get a smaller singing role.
When you do an acting audition, you don’t have to learn the script.
Just read it enough times that you are familiar with it. You can hold the script in your hand during the audition.
If you are auditioning for Dorothy, you might have to read with other auditionees, so become familiar with all the Dorothy scripts. Don’t learn them.