Trying to install PHP 3.0 to Wordpress 2.5

I downloaded PHP and have the zip folder on my desktop.

Go to install new plug-in, upload the zip folder, click install, and I get:

Unpacking the package.

Installing the plugin.

Destination folder already exists. /home/content/22/5228622/html/wp-content/plugins/phpBB3/

Plugin Install Failed.

Anyone know what's going on here?

I tried deleting and redownloading all the PHP files and I still get the same result.