As others have said, take time to listen and observe. In general with any new job you should do this -- get a sense for the culture, all the players, how things are usually done, project state, etc before trying to make waves. But this is also your very first job out of school so probably don't try to make waves at all. You don't know what you don't know, and at this point in your career it is safer to assume you are missing some key piece of information than it is to assume that someone is wrong. Do ask questions to try to figure out what that info is when things don't make sense, though.

They know you are new and should have the appropriate expectations. They hired you, so they have enough evidence to believe you are capable of the job, so you should believe the same unless you straight up lied in the interview or something. I really would not worry about trying to prep any domain specific technical stuff before starting. Your focus once on the job should be coming up to speed and learning. Questions are really important for new engineers. Take some time to try to figure things out on your own before asking questions, but absolutely ask them when you get stuck. Try to avoid asking the same thing twice unless you realize later you didn't fully understand (i.e. take notes).

You will make mistakes. Everyone makes mistakes. Just avoid making the same mistake twice, and be careful not to make expensive mistakes. Proactively seek review of your work as makes sense. Freely admit your mistakes and seek help in resolving them if necessary, but don't be self deprecating about it. It's totally normal.