You should install divine in order to execute this example.  The file
tests/ltsmin/README in the tarball contains some instructions about
this, but I seem to recall someone complaining about the fact that
most of the links in this file were dead now (patches welcome). For
what it's worth, the copy we use for generating the Debian package of
divine installed on the sandbox is at
https://gitlab.lrde.epita.fr/spot/divine-ltsmin-deb