Understanding Export Content Documents or Files and Permissions Needed Using Salesforce Data Loader

By default, if you export files from Salesforce without filtering the results by ID, Data Loader only exports Content Documents that are owned by the user or directly shared to the user running the export.

In order to successfully export or query all Content Documents and files in the org, the permission 'Query All Files' must be enabled in Profile or Permission Set via Administrative Permissions or App Permissions. 

This permission enables the ability to query ContentDocument and ContentVersion and retrieve all files in the org, including files in non-member libraries and files in unlisted groups.


Notes:

• Available in Lightning Experience and Salesforce Classic in Professional, Enterprise, Performance, and Unlimited Editions.
• Exporting using Data Loader doesn't obtain the physical files you’re attempting to back up from Salesforce. The output contains  CSV-formatted files for backup purposes.  The Data Export through Setup allows the download of attachments, images, and documents in addition to the CSV-formatted files.  CSVs will contain the details of the files for each object, where the folders have the actual content/attachment/document. The Data Export is not available in your Sandbox org. See the Support Video on How to Export Backup Data from Salesforce to see an example.