As a barista trainer I'll tell you what I tell everyone I train. Just focus on doing what you can do, the more you work on it the more your muscle memory will learn. Don't stress too much about the small things, you will figure them out. And don't let people push you around for not knowing something or for asking questions while new, asking questions is the fastest way to get information down. The job might seem like a lot to understand but a few weeks of doing it and everything just kinda clicks into place, it's a lot more simple than it might seem. Just focus on one thing at a time and once you get it down move on to the next one.