HI 
M4 is a figure which is built for use in Poser, or Daz Studio,. and , since Daz studio is free right now, (if you want to) you can download that, and install M4 into there.
If you don’t have Poser,. or Daz Studio installed,,. you should still be able to browse, and install M4 base into another folder. (see pic) and then you’ll need to Add that location to Carrara’s browser.
It’s recommended that you install any “content” files to somewhere like,.. My Documents / My 3D Library /
Daz Studio,. and Poser both create a set of folders, which can be viewed in Carrara’s browser,. (Content / Runtime) folders.
You can Add a “Runtime” to Carrara’s browser, (see pic) and it will display a set of categories, ..Figures / Poses/ Props / etc..
From the browser in Carrara, you can load M4, into a scene, by double clicking the thumbnail image in the Figures / Daz People / folder.
you can then add clothing, and hair to that figure.
Hope that makes sense 

Click thumbnail to see full-size image