Extract the ERS folder to your addons directory.

Copy the report.php file from the ERS directory to your web server and then delete it from the ERS directory as it's no longer needed there.

Browse to ERS/lua/autorun/server/configuration.lua and change the settings to reflect your personalization. If you leave these default, the script will not work.
Browse to your web server and open report.php and change the from: and reply-to fields. If you forget to do this, it will appear as though your reports were sent from my domain. The script will still work, it may just be confusing.