Block quiz-exam for users from instructor panel

Hello, I have a case where I need the exams-quiz for one of the courses, to be locked because the user has to schedule an appointment with the instructor so that they can arrange a Zoom call before the quiz. After that, the instructor should allow the user to take the quiz. Is there any functionality that might help on that? Also, any suggestions on how to implement this on the user perspective? I mean right now, instead of the quiz there is a contact form to schedule the call. but I would like to display on the curriculum of the course that there is the exam but is lockedd.