I am trying with Mate 17.04 in VirtualBox. The add-apt-repository runs without problems, but when I try to install the ltps-manager package, I get the following message:
“E: Unable to locate package ltsp-manager”
LTSP manager has been explicitly packaged to run in 16.04 LTS I think. I imagine an 18.04 LTS version will come along in due course. But, for now, it’s only for 16.04.