Hi @Jn-ef8,
For QuickBooks Online (QBO) to work with a Mac system, you need to at least have OS X El Capitan 10.11, or better.
An internet connection speed of at least 1.5 Mbps or faster is suggested for a smooth experience.
If you're referring to QuickBooks Desktop for Mac 2021, the oldest operating system it will work with is OS X 10.15 Catalina. Additional details on system requirements are on this page: QuickBooks Desktop for Mac 2021.
Check out this page to see a list of fixes, improvements. and changes made to QuickBooks Desktop for Mac 2021, per update release: Release notes for QuickBooks Desktop for Mac 2021.
I'll be around if you have other concerns with QuickBooks Desktop for Mac. Tap the Reply button and post a comment below, and I'll handle it for you.
