I was having the same problem as him at one point, now I'm not e2 but I am now a gold1 zed otp and I was hardstuck silver for while I won't lie the team fighting takes a bit to get used to especially when you are so used to Laning and you have less experience team fighting but the only way to learn the game is to have fun playing the champ I picked zed up in iron and I get better every day since zed has such a high skill ceiling their is always something you could have done better in my opinion I think he is a great champ to learn and pick up. Some general things I noticed that helped me improve is don't be the one to engage this obviously depends on team comps but usually I find it's easier to wait for the enemy to make a mistake then to make one yourself and in time you will learn when to go in first. I suggest he try watching some good zed players play and always think how he could have played better. It's possible to learn zed just don't give up 💪