Default port in CA config does not match default kea-shell config
The example config that gets installed in /etc/kea/kea-ctrl-agent.conf uses port 8080, but kea-shell uses 8000 by default.
As a result, in the default configuration you need to pass extra switches, even though the software could work out of the box.
To upload designs, you'll need to enable LFS and have admin enable hashed storage. More information