In that publication, we used my old implementation which was interfaced to an earliest version of Psi4. It is not working with the current version of psi4. It needs a significant revision to make it compatible with the current version.
However, I am going to implement a fresh DF/CD-OCCD code in the near future, as a requirement of one of my active grants. We may include DF-OCCD in the next release of Psi4!