Navigate to the Add-Ons Panel within your Jira installation in order to access the Herzum Approval Administration Screens.
Jira ADMINISTRATION → Add-Ons → HERZUM APPROVAL

Furthermore, Project lead, Jira System administrators and users in project role administrators can setup a specific approval workflow for a single issue.
Navigate the issue where you have one of the permissions mentioned above in order to manage this setting.
Issue View screen → Issue Approval
