In Knowledge Base the function used to subscribe content is called Watch.
Step 1 - Open the KnowledgeBase then, select the page you want to get notified from.
Step 2 - Click on the 👁️ icon located at top-right of the page.
Step 3 - Check Watch all content in this space; to receive updates from the entire space
OR Click Watch page; to receive updates from the specific page only.
You'll receive email notifications for:
Pages / Spaces edits whenever any changes is added to, edited, or deleted.
Attachments, including new versions or deletions of an existing attachment.
Comments, including new comments or deletions of existing comments.
To stop watching the page or space, uncheck the relevant check box.
You can review your watched content (subscription) on KnowledgeBase and stop notification -How to stop notifications from Knowledge Base (Confluence)?