Yes. Min and Max Requests located in Settings> Course Request Setup need to have a value in order for Course Requests to work.

Does the course setting for max number of requests lock down future requests?

At this time the course setting for max number of requests does not lock down courses from additional requests being made.

For example, on the Course level, if you've set the max number of requests to 17 and a student is the 18th to request the course, the system does not prevent the student from requesting the course.