I would gently remove the need to apologise.
The first time he says sorry, a teammate or coach can simply reply: “You don’t need to apologise for trying.” Then move straight on.
I would also look at the environment around him. Even if nobody is criticising him directly, does the group react loudly to mistakes? Do adults sigh? Does he hear lots of “you should have…”?
Children can build the idea that mistakes inconvenience everybody without anyone intentionally teaching it.
In training, praise recovery after losing the ball. That shifts the success from “never make a mistake” to “what do you do next?”
I would not repeatedly tell him to be confident or make his apologising a big public topic.
The goal is for him to discover that mistakes are normal football events, not social failures that need an apology to the group.
