Am I correct that dmake is not the default make? That the makefile assumes make or nmake?

It all depends upon $Config{make}. When the 'perl Makefile.PL' step of the module build is run, it will generate a Makefile suitable for whatever flavour of make is reported by $Config{make}. (Easy way to find out what $Config{make} returns is to run perl -V:make)
The various flavours of make have slightly different rules of grammar - eg 'make' won't understand a Makefile that has been written for 'nmake'. You need to run the specific flavour of make for which the generated Makefile has been written.

Cheers,
Rob