Unpack project's archive to your game directory ('e:\games\duke3d' in my case). Ensure that as a result, project files get located in the same folder as GRP file.
Start Setup_w32.exe to configure sound settings and screen resolution.
Save configuration, close setup utility and start duke3d_w32.exe
As far as I know from official 'readme', it supports playing external music in various formats and adds some network playing as well. No graphic improvements here.