Marsh, 16, will compete with the Under-16s, having committed himself to the club last month.
Commenting on the forward’s arrival, Academy Director Gary Issott said: “We’re really pleased Zach has decided to join the club. He’s a talented young player with a bright future if he continues to work hard at it.
“He’ll have the best chance to do that through our new facilities and the brilliant structure at this Academy, which are both key in attracting players like Zach. I wish him the best of luck for the next few years and am confident he can take the opportunity he’s earned with this club.”