Cyberduck config no longer working

[kitchensinkodysseus]

I'm trying to set up Cyberduck to work with Secretive; I already use Secretive for shell ssh access, and it works great.
I added the plist as per the FAQ, but I'm not sure whether there is more config required as nothing is different in Cyberduck. When logging in, it fails due to no password supplied; and there's no path to give it an SSH private key.
I had a look at the xml in the plist, and although I admit I don't understand it, I noticed it calls "$HOME/Library/Containers/com.maxgoedjen.Secretive.SecretAgent/Data/socket.ssh".
I don't have this file, and in fact don't have this folder. In $HOME/Library/Containers/ I have Secretive/ and SecretAgent/ but no com.maxgoedjen.Secretive.SecretAgent/ folder. However, tweaking this line to point to SecretAgent didn't work either, unfortunately, so I might be wrong to have changed it.
I'm on MacOS Sequoia. Can anyone help with how I might fix this or update it for my machine?
Many thanks!