There two options for now, in order to get the phpBB Bridge.
The one is to copy the whole folder named wp-phpbb-bridge under the /wp-contents/plugins/ in your wordpress installation.
The second is to downloaded directly from out web site http://www.e-xtnd.it/wp-phpbb-bridge/ that has the latest version (2.0.7).
Even if your theme is too old, if you following the WordPress updates, then you can modify easily your theme in order to allow widgets usage.
Following some tutorials you can follow, in order to register new widget areas in your theme:
I hope that helps :)