Some Mac apps require a browser round-trip to authorize an account. Safari won’t always cooperate.
Many websites that offer financial services (such as banks and investing companies) let you connect your accounts to other software, such as Quicken. However, it’s often unwise to let any third party see your login credentials. The workaround is that you can start at the app, which switches to a browser in which you log in directly to the site in question and authorize the conduit, and then the site provides a token directly to your app to allow data to flow.
I’ve found lately that this process fails as often as it succeeds when I use Safari.
