Welcome to the Community, @luckyuser9.

Thanks for taking the time to reach out to the QuickBooks Community for support. It's great having you here. 

If you're using Windows, you won't be able to open DMG files directly since these are MacOS disk image files. Otherwise, ensure to use Mac OS X 10.9 (Mavericks), 10.10 (Yosemite), 10.11 (El Capitan).

To ensure you get the guidance you need to open dmg files seamlessly, I recommend contacting our Support Team. They can communicate with you directly to provide instructions. 

Here's how:

1. Go to the Help icon and choose Search.
2. Click the Contact Us button and enter your concern.
3. Press Continue.

See this article for our operating hours so we can address your concerns on time: QuickBooks Online Support. It includes the contact number you can use to call us directly.

Please feel free to get me in the loop if you have any more questions about your QuickBooks file. I'm here to lend you a helping hand anytime.