It seems that if you are a teacher you can get one.
This is a quote from the Wayne State University Press website:
"Teachers: When ordering Latin via Ovid and the audio material, be sure to order the free Teacher's Manual (not sent to students) that contains all of the translations of the Latin stories, plus each chapter's Exercise V, which requires the translation from English into Latin. Games and songs are included.
Please request this guide by calling us at 313-577-6126."
You usually have to prove that you're a teacher by school letterhead or a school shipping address.