Can anyone assist with how to do this

 

Dude.. dll are for windows users. if you really need to use dll and only got a mac install Bootcamp and s*** be done aight?

 

Why do you need a windows binary on your mac? What is your end goal?

 

I'm just guessing here

OP downloaded a K´ed Software for Windows and think it will work on a Mac as well

Nope you'll need an AU or VST file instead of the .dll (If I´m guessing right here too)
(there is a way to bring even a .dll to work on a mac but that´s a bit complicated and does not work with every .dll ) (If you understand German this is the way
https://www.beat.de/ratgeber/endlich-windows-vst-plug-ins-macos-nutzen-10075844.html )

But we need more info which Programm/ Synth or Whatever you´ll use

 

Good luck!

 

Well He is not Totally Stupid Circa 2012 there was VFX machine which wa a sort o wine app for running Vst s on Mac
you can read for the sake of Plugin history
http://www.smproaudio.com/index.php/en/products/v-machines/v-machine-downloads#mac-osx