You will need to install GW2 Addon Loader, instructions on installation found here: https://github.com/gw2-addon-loader/loader-core#installation
Alternatively, you may use the Addon Manager for an automated install
Download the latest gw2clarity.zip from the Assets section found here: https://github.com/Friendly0Fire/GW2Clarity/releases/latest
Copy all files into <Guild Wars 2 installation directory>/addons/gw2clarity/.
Configuration keybind is Alt+Shift+P. First create a Grid, then add buffs to the Grid. Grids can be assigned to Sets to quickly toggle which Grids are visible (e.g. to disable raid overlays in open world).
Currently unavailable in competitive modes.