How to Install Master Presets on Studio One
Unzip and move preset file or folder to "User"/Documents/Studio One/Presets/PreSonus/FX Chains (If the "FX Chains" folder isn't there, just create it yourself.)
Open up Studio One and in the top left menu bar under View make sure "Console" is checked
In the console on the right hand side you should see a channel strip titled "Mix FX" - Click the little arrow to the right of where it says "Inserts" to bring up a menu. Locate the preset and click on it to activate!
Enjoy the sweet sound of a well-mastered song!