Do you have to make appointments to workout at this gym or is that something you only need to do if it's super busy?

I don't think appointment is necessary. I am going to that gym almost every day, and no one has ever asked me whether I have an appointment.

You can make an appointment to guarantee your spot if it gets busy but no you don't have to. It's a fall back plan for them to keep track of how many people they have in there. That's what I was told by staff.