The link from the install walkthrough takes me to the Docker site, where I find that the reason the stock Ubuntu Docker (which appears to be 1.13) complains in -compose is because Xibo wants Docker 2…
which appears to be commercial these days, and not FOSS anymore at all.
jra@pano:/appl/downloads/xibo-docker-1.8.9$ sudo apt-get install docker-ce
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package docker-ce is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package 'docker-ce' has no installation candidate
Oh bother. Yes, I’ll bet you cash the machine has a 32-bit install. Oops. I know I had a good reason for that when I did it, but I don’t remember what it is anymore.