They are using a rustc from August of 2022. If you installed that version, made a new project, and asked for the latest clap, it would not shock me at all if rustc were too old.
EDIT: from clap itself:
> We will support the last two minor Rust releases (MSRV, currently 1.70.0)
EDIT: from clap itself:
> We will support the last two minor Rust releases (MSRV, currently 1.70.0)
So yeah, 1.63.0 is going to be quite old.