You see this error when you try to use the app: "SharePoint Connector for Confluence needs permission to access resources in your organization that only an admin can grant. Please ask an admin to grant permission to this app before you can use it."
This happens when your organization's user consent settings in Microsoft Entra ID restrict who can consent to apps. The app's permissions are delegated, but your Entra ID policy requires an administrator to approve them on the users' behalf.
To resolve it, an Entra ID administrator grants consent for the whole organization: Embed a SharePoint document or list macro, sign in as an admin, and choose to consent on behalf of your organization. For the full procedure, see Grant Microsoft consent.
For background on the consent settings, see Microsoft's guide on configuring how users consent to applications.