flukadpm is the name of the default executable when DPMJET (or RQMD where applicable) is requested. You can find a very good description here:
If you have user routines (and you need DPMJET), you have to select the appropriate linker (ldpmqmd instead of lfluka) to produce your executable. This is described here: Working with user routines | The official CERN FLUKA website
In case you have questions that do not match the original thread, please do not ask them in the same one. Ideally, we aim for one question/problem per thread.
Cheers,
Daniele