Open the zip and extract all contents to a folder.
Double-click `osuMapCombiner.jar` or open a command prompt/terminal window and type the following: `java -jar osuMapCombiner.jar` to start the application.
Then find and add your maps to the interface (can be drag and dropped in). Once that's done generate your marathon and you will be ready to play it!
osuMapCombiner requires Java 8 or higher. If you cannot get the application to run, please update your Java version or install a later release of Java.