To use AutoPage, you need to set up an application link between Jira and Confluence (see Atlassian's Application Link documentation).
If there are multiple Confluence application links in Jira, AutoPage uses the primary Confluence application link.
We recommend that you configure the application link to use "OAuth with impersonation". In this case, users do not have to be logged into Confluence to generate a page via AutoPage.
When using "OAuth authentication", you must ensure that the user is logged in to Confluence before generating or updating a Confluence page using AutoPage (see also the documentation for OAuth security for application links).
Permissions in Confluence
AutoPage creates Confluence pages as the Jira user who is currently editing the issue. The user must have access to the space where the Confluence page will be created. They also need permission to create pages.
The Confluence template which is used to generate a Confluence page, must be located in a space where the user has read access. You can restrict template editing using page restrictions (see the documentation on Page Restrictions). The page restrictions must not restrict visibility for the user.