Reading from the activity, it still seems to receive some fixes and updates although, as the SlackBuild author said, it would not be advisable to use it in an internet-facing desktop for security reasons.
NsCDE also behaves very well.
Otherwise, you can use Xfce which was heavily inspired by CDE; and now, even Plasma 6 have a very good CDE-like (or Motif) theme.
You can download the original CDE here: https://sourceforge.net/projects/cdesktopenv/
Reading from the activity, it still seems to receive some fixes and updates although, as the SlackBuild author said, it would not be advisable to use it in an internet-facing desktop for security reasons.
NsCDE also behaves very well.
Otherwise, you can use Xfce which was heavily inspired by CDE; and now, even Plasma 6 have a very good CDE-like (or Motif) theme.