Hi Gina,

For the ePub Exporting option to be available to courses, it has to be at least unlocked in your root Canvas account (and then any subaccounts the course is under).  Having the option unlocked simply means instructors will have the choice to enable is in the course feature options area.  Since you don't see it in the feature options area, I will guess it's disabled and locked that way either at the root account level or in one of the subaccounts that this course is contained under.  You can check the account settings -> feature options pages you have access to and unlock it if you have the access.  If you don't see it, you may need to contact your primary root Canvas administrator (assuming that's not you) to unlock it at the root level.

Hope this helps!

-Chris