Enabling document numbering in your bundle will number documents in your bundle sequentially. These document numbers will be displayed on the index entry for each document and on the document page in the bundle.
To enable document numbering, first navigate to the index and pagination settings by clicking the "Index and Pagination" row on the bundle building page.
This will reveal a side panel on the right containing the index and pagination options. Expanding the Index Settings section will allow you to toggle document numbering on and off.
If you've already generated your bundle before changing these settings, please regenerate your bundle again for the changes to take effect.