No, you didn't read that wrong: I'm asking you to do 75 pull-ups. As a warm-up.
I have a lot of fun doing these, and I think you'll find they're pretty addictive. You don't have to just belt them out one after the other without rest, though! Use any set and rep scheme you want, and any pull-up variation you like—whatever helps you get through them.
However, if you're unable to do any pull-ups or know that doing 75 of them is going to absolutely wreck you for the rest of the workout, then feel free to cut the reps. Try, though, to get at least 30 reps.
I also suggest that you try chin-ups or use bands to assist you. You can also do jump pull-ups, or negative reps. The point is to use the movement to warm up and pre-exhaust your back.