If you simply install this great plugin it will only work for super admins creating sites within the admin panel. If you want this plugin to also work for visitors creating a site by registering from the front end of your site you must make a couple simple changes.
1. create a folder called "mu-plugins" in the /wp-content folder
2. move the "default-blog-options" folder from /wp-content/plugins to the newley created /wp-content/mu-plugins folder
3 move all of the files and folders WITHIN the "default-blog-options" folder to the root of /wp-content/mu-plugins
Once you have done this wordpress will automatically detect that the mu-plugins folder exists with files in it and execute them. This will allow your default blog setting to work for all blogs created on your site.