On macOS default security settings prevent running arbitrary executable files downloaded from the internet, so you'll need to approve the FireFly CLI. You will only have to go through these steps once after installing, or updating the FireFly CLI. The first time you try to run ff in your terminal you will likely see a dialog like this. Simply cancel this dialog.
Now try running the ff command in your terminal and a final confirmation dialog should appear. Click open:
This time the ff command should succeed and you should see something like this in your terminal:
