Intuit has long intentionally gone out of their way to make sure the Mac and Windows versions of QuickBooks are incompatible. You can't just bring in the database from Windows and have it open straight up in the Mac version, or visa versa. The Mac version also still doesn't have many features the Windows version does.
Fortunately, you have used QB for the common, simpler bookkeeping functions, so what you have will transfer over easily to the Mac version.
As Csound1 noted, if you can keep a Windows box setup just for QB, do that and leave the database where it is. That provides the best compatibility for sending out your database at year end for accounting review and have it sent back seamlessly.
To do that in the Mac version, you have to choose to Back Up to QuickBooks for Windows. This converts your incompatible Mac data to a mostly Windows compatible file. Your accountant imports that data, goes over your books and then has to choose to export it for Mac. Even in simple accounting, things don't translate. Intuit knows this and they warn you about it. But basically, they don't care about Mac users. This is such a highly known way to screw up a QB Pro for Mac database, that an accountant would prefer to come to your place of business to do year end corrections on your Mac. That's what our accountant does.
If you would still rather be able to do all of your work on one computer, export the Windows QB data for Mac. Bring that data over to your Mac and import it into QB for Mac. Once there, consider it stuck in the Mac version of QuickBooks and never export/import it again.
