Post length for beginner

I was looking at the Unicycle.com site and entered my beginner info (age, height, inseam, etc.)

It of course came back with a 24-inch Torker recommendation, but to order I have to know the post length. I’m a beginner and I wouldn’t know the answer to that. I don’t do trails, distances, etc., because I haven’t gone beyond two pedal revolutions on a borrowed 20". So how would one answer that question?

I’ve looked at a lot of messages on this board and find people talk to beginners in jargon that I don’t understand when they answer questions. I.e. what does “muni” mean?

How would I know how long cranks should be? What’s a crank? Why is length better or worse for some people? Do I determine this later, after I learn to ride? Or do I buy the wrong length now and bitch about it while trying to learn? I’m 66 years old and probably won’t be hopping on/off park benches or riding trails. I will probably only be riding around the neighborhood, which has some short and long hills and everything is paved.

I’ve read a lot of stuff on the web and everyone offers expert advice that makes no sense at all, only to find out that the person is an avid “biker(?)” bragging to the beginner by using terminology the beginner doesn’t understand. A lot of the answers to people are a bit arrogant.

Simple question, then, What length post and why would a longer or shorter post be advantageous to anyone?

Thanks, from Ohio, USA
Old Martian