Download this and you will have dw.dll:
https://dbsoft.org/dwindows/dwindows-win64-3.2.zip
Pelles C currently not work with dwindows. There are many errors spit out on dw.h and the most important is Pelles C said dw.dll is invalid.
Please have a look at this.
Thanks.
Update: this is the bug report to dwindows developer on the dwindows forum:
https://dbsoft.org/forum/showthread.php?tid=87
I'll have a look next days.
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.