By default your devZing Bugzilla is configured to be private. That is a user must log in before they can see a defect.
If your project is open to a wide audience you may want to let anyone view bugs. This can be accomplished by changing the requirelogin parameter.
From the Bugzilla Main Page, navigate to:
Administration / Parameters / User Authentication
Scroll down the page to this field:
Change as appropriate and click Save Changes at the bottom of the page.
You will want to also review the self registration settings. See http://docs.devzing.com/configuring-self-registration/