To download, click the "download ZIP" button to the right --> To install the stylesheet: 0. unzip this repository in one folder, 1. open install.m in Mathematica, 2. click the <Run Package> button on the right top, 3. quit Mathematica and restart, 4. should be able to find in the menu: Format>>Stylesheet>>Cambria Article and Palettes>>XRef Palettes, just pick the stylesheet to apply.