Yes, CalculiX doesn’t have any CZM (unlike Abaqus). Might be better to ask for workarounds (especially involving subroutines) on its forum.
When it comes to workarounds with built-in features, there’s just no separation contact (not predefined, needs a specific setup) and you could add a thin layer of elements with a specific material model (including no tension or no compression, orthotropy and so on).
You could also try using some UELs from Abaqus. This particular application is mentioned here: User Element Troubleshooting - CalculiX (official versions are on www.calculix.de, the official GitHub repository is at https://github.com/Dhondtguido/CalculiX).
Regarding subroutines in PrePoMax, check this thread: UMAT option in PrePoMax
However, I would also consider using a different solver such as Code_Aster - I think it has CZM. Or even OpenRadioss if you need explicit dynamics.