Try opening the QIF files in Apple's Numbers, via File>Open. What happens when you double-click on the QIF file? Does it want to open in Quicken?

I second the the choice of MoneyDance. It is very stable, mimics a lot of Quicken "style". Check out QIF Importing with MoneyDance. In the sidebar on that same page are links to possible problems and importing for a Mac from other versions of Quicken.

On a Mac since 1984.
Currently: 24" M1 iMac, M2 Pro Mac mini with 27" BenQ monitor, M2 Macbook Air, MacOS 14.x; iPhones, iPods (yes, still) and iPads.