The error "Authentication Error - can't grab global config from db. (6006)" is usually due to a permissions problem during installation. You should first complete setup by generating the configuration settings appropriately. Then, run the Urchin inspector and let us know the results if any additional errors or permissions problems are indicated.
Configuration:
Running the Urchin Inspector: While still in the ~urchin/util directory run ./inspector from the command line. This will print configuration statistics to the screen. If there are any errors or indicated permissions problems, please submit a request to our support department. If not, you should be ready to complete setup by logging into the Urchin Administration with a web browser.