Cannot Find Package for Ubuntu 20.04.5 LTS

[KerickHowlett]

I attempted to install this the yubikey-agent package with sudo apt install yubikey-agent onto my WSL2 image of Ubuntu 20.04 distro, but I get a "package not found" in response—even after running sudo apt update.

Is there a specific registry I need to add first?

Or is it just not available for my version of Ubuntu? Even though it's the latest version available for WSL2, I know it's not the latest Ubuntu version out there.