Opening it the first time

macOS

Unzip the archive and drag QuickKey into your Applications folder, then open it once. macOS will refuse, saying it cannot verify the developer. That is expected.

1. Open System Settings, then Privacy & Security.
2. Scroll to the Security section. A line reads QuickKey was blocked to protect your Mac.
3. Click Open Anyway, authenticate, then confirm in the dialog that follows.

On macOS Sequoia and later this is the only route. The old shortcut of right clicking the app and choosing Open no longer bypasses the check.

If macOS instead says the app is damaged and cannot be opened, the quarantine flag survived the unzip. Clear it once in Terminal and open the app again:

xattr -dr com.apple.quarantine /Applications/QuickKey.app

The first time a key sends a shortcut, types text or hits a media key, macOS asks for Accessibility permission. QuickKey shows a banner with a button that opens the right pane. The permission is tied to that exact copy of the app, so grant it again after you replace the app with a newer build.

Windows

Windows warns too, but more gently, and it never refuses outright. Run the installer and Microsoft Defender SmartScreen shows Windows protected your PC.

1. Click More info on the SmartScreen dialog.
2. Click Run anyway.

There is no equivalent of the macOS damaged-file error, and no extra permission is needed to send keystrokes. Windows 10 and 11 supply the USB serial driver for the deck automatically.

Why the warnings happen

Both systems check who signed an application before running it. The macOS build is signed ad hoc, which is enough to run on Apple silicon but carries no identity, and it has not been through Apple's notary service. The Windows installer is unsigned, so SmartScreen has no reputation to look up.

Neither says anything about what the app does. Clearing them for good means a Developer ID certificate and notarisation on the Apple side, and a code signing certificate on the Windows side. Both are on the list.