The hardest part for me was to find an example to compile, or a tutorial on usage of dwindows (doesn't seems very popular). So I downloaded a Pascal sample and converted to C, then downloaded the win64 version of "dw.lib" (the one you showed).
Put together, and without any change in the headers compiled and runned without errors...
I attach the project, including the library, for your crosscheck.
P.S. You should ignore the linker warnings:
POLINK: warning: Realigned section '.idata$2' in object 'dw.lib(DW.dll)' (from 4 to 1 byte(s)).
POLINK: warning: Realigned section '.idata$3' in object 'dw.lib(DW.dll)' (from 4 to 1 byte(s)).
They refers to MS misaligned sections that are simply realigned on 1 byte boundary.