As the script is Open Source and GNU GPL licensed, you are encouraged the use the script for yourself on your own server/webspace or even modify it (but you have to make your changed version Open Source and GPLed, too).
For detailed instructions on how to install the script, check doc/INSTALLATION within the Source Code .zip-file.
If your installation was successful, you can decide whether to...
... only use the script for yourself:
There is a mode for realizing that by fixing the counters to your information only so that it won't have any use to other users. See inc/one_user_mode.php for details!
... provide a public mirror of the script:
If you have got enough bandwidth for enabling other users than only yourself, it would be great if you could add your server to the mirror list. This helps dividing the mass of signature requests on each server and therefore reduces the average load!