QuickBooks for Mac 2013 and above uses a different process for backing up data, and requires a different process to restore backups.
When a data file is backed up in QuickBooks 2013 and above, it creates a disk image (.dmg) file. Each disk image QuickBooks creates when it backs up your data includes a copy of your company file and your Attached Documents Library (if you use and back up attachments).
If you need to restore your Attached Documents:
To restore qbmb or .mac.qbb non image backup files created in versions prior to QuickBooks for Mac 2013 or any QuickBooks for Windows versions:
If these steps do not resolve the issue, you can read discussions and post messages and questions relating to your issue on the Intuit QuickBooks Community site for free or you can contact a technical support agentfor additional guidance. Fees may apply.