Thanks for getting back to us, @Cyd.

Allow me to step in for a moment and help make sure that you can backup our company file.

First of all, I appreciate you following the steps provided by my colleague. Since you're still unable to create a backup copy of your company file after running the verify and rebuild utilities, I highly recommend contacting our QuickBooks Desktop Mac Support. They have tools such as screen-sharing (remote session) that can pull up and check your account and investigate why you're having this issue.

Here's how to reach them:

1. Click this link: QuickBooks Support 
2. Choose QuickBooks Mac Desktop, then type-in Technical Support on the search bar.
3. Select Get the Phone number (green button) below.

Just in case, you can also visit this article for future reference: Restore a backup (.dmg) in QuickBooks Mac.

Thanks for being a part of our QuickBooks family. Please let me know how it goes after contacting them. Please leave a comment below should you have any follow-up questions or concerns. I'll be here to help you out. Have a great rest of the day!