Hi Lisa,
in order to be able to access to the quiz, the user will have to synchronise with the server so the SCORM data is sent to the server and the quiz activity can be unblocked.
Offline support and activity access restriction based on completion does not work very well together because all the logic to check completion is at server level and also, because we can't download in advance all the required data of an activity that is blocked (not accessible) to the user, it will be a security problem.
Regards, Juan