Unable to locate `kwallet-pam` package in Debian (bullseye) even though the package exists in the source

I'm trying to install kwallet-pam package in my Debian 11 with KDE Plasma so that I don't need to type in wallet passcode at every boot. But apt update then apt install kwallet-pam says E: Unable to locate package kwallet-pam, despite the fact that the package is in the source! : https://packages.debian.org/source/bullseye/kwallet-pam What am I misunderstanding / how to resolve this issue?