Latest Roon Server is not available for download on NixOS

How do you build packages for NixOS? Are you essentially curl'ing down the binary from Roon Labs and then re-distributing it? If so, I don’t think Roon Lab’s copyright allows for that. When the end user types nix-env -iA nixos.roon-server, this should result in a download from download.roonlabs.com to their system.