Unable to install pirate-audio software

I’m trying to install the software for pirate-audio headphone amp on a new install of bullseye.
32 Gb sd card.
The first error message I get is Hit : 1 http://archive/.raspberrypi.org/debian. buster InRelease
some lines omitted
The following signatures could not be verified because the public keys is not available : no pubkey78fd980e2710d2943 Updating from such a repository can not be done securely and therefore is disabled.
The install then skips this package and goes on with the rest of the install. The Iris web host is not created and the rest of the tutorial fails.

I was doing this headless over vnc. Please ignore the screen background The issue seems to be that buster is in the process of being depreciated. The pointer to the repository will have to be updated to bullseye if the packages have been ported to the right places.

I have the exact same issue tried installing this the other night and thought I was going mad, an exhaustive Google search threw up nothing, especially when people had recently posted positive reviews!!
Let’s hope this gets resolved quickly

I have been having the same problems/issues gave up and sent it back to Amazon. Give me a shout when it’s fixed.