Did you just copy and paste what was written in the coincashew you manual? You should at lest try to understand what you are doing and how the different parts play together.
You made a cardano-node.service file which you deploy with systemd with
sudo systemctl start cardano-node
in that file, in line 11, as it says in the log message you have the start up script mentioned. And systemd could not find the
cardano-nodecommand in that script. That could mean your PATH env variable is not set right or your cardano-node executable doesnt exist or at least not where it is supposed to exist.