You have to define initial permissions for a new HelpDesk users who are register through HelpDesk Sign Up. Go to JIRA Administration menu/Add-ons/HelpDesk and specify the JIRA groups and don't forget to allow public sign up:
You are viewing the old version of the documentation. See the latest version here: [HDJS : Helpdesk for Jira Server Home]
Overview
Content Tools
Apps