Explain Sub Same Day to me like I'm 5

Since I moved to another state I have all the options now, before I only had one dot com station. My new state has Whole Foods, SSD, and 2 dot coms. Apparently only the SSD shifts surge here so I wanted to try it out and I like to learn about it before I do it.

So are the packages just not numbered with driver aids, and can I just throw them in my car willy-nilly witbout organization?

Are the stops numbered on the app or do I just manually select the closest address to where I am at?

When scanning in for work who checks you in with your ID? Do I find a cart and scan every package in individually, or is there a route code to scan?

Any tips are appreciated, and yea remember I'm 5 so dumb it way down for me. I sincerely miss having surge pay so I need to try SSD.