Fatal error after installing and testing plugin

I installed the plugin by browsing to the zip file and uploading. It is WP version 4.1, and the latest version of the plugin.

I created a test user, and then created a community. When creating a post (with the admin or test account), I get this.

Fatal error: Call to undefined function get_active_blog_for_user() in /opt/lampp/apps/wordpress/htdocs/wp-content/plugins/communities/communities-framework.php on line 857

When trying to read a post on the message board, I get this error:

Fatal error: Call to undefined function get_active_blog_for_user() in /opt/lampp/apps/wordpress/htdocs/wp-content/plugins/communities/communities-framework.php on line 1772

I'm running Wordpress on XAMPP, installed by Bitnami. The only active plugins are WPMU plugins, and I have not made any edits to the code. It is not a network site.

Also, do you have any information on customizing the interface, for example on how to put the communities link up top on the horizontal board, and changing the HTML & CSS for the communities display screen in the dashboard?