Did you install TeXLive from a Debian package or directly from the files at tug.org? I suspect the latter? And did you build cadabra from source or did you install the binary package?
Things should work if you first install TeXLive and then build cadabra from source. During the '
cmake ..' stage, you should see a line like
-- Installing LaTeX style files in /usr/local/share/texmf/tex/latex/cadabra2
What does it say there for you?
The pre-built binary .deb packages install the cadabra style sheets in
(because that is where the TeXLive from the Debian repositories expects style files to be). If your new TeXLive does not look there, you need to build from source or set the
TEXINPUTS environment variable before running
Let me know if this helps.