The installation package should work on Joomla 2.5. One of the most common reasons that we see for failing to install is a configuration of your server for PHP upload size cap. Please check out our "The installation package fails to upload" topic on our
Common Support Questions
. If this doesn't help, please include any error messages that you are seeing when performing the installation. With that information, we'll be able to help narrow down the cause.
-Melissa