All Macs use Apple’s Gatekeeper feature to keep tabs on the apps you are downloading and ensure they are free from bad code and malware. App store curators routinely check app signatures to warn users when an app is downloaded from a source outside the macOS App Store. By default, it allows you to install apps outside the App Store by known developers, with a legitimate, Apple-issued key. But sometimes it’ll attempt to block software when it can’t be sure it comes from a trusted source.
And while no one would argue that the macOS App Store is the safest place to download applications, there will always be times where you need to venture outside of it for the software you need. In these cases, don’t be surprised to see a pop-up that warns you of the risk of installing software from unknown developers.
Though annoying, it’s still a click away from downloading and installing as normal. Gatekeeper, however, sometimes blocks unsigned apps, making it appear as if you can’t use them on your Mac. Luckily, there’s an easy way around these restrictions.
1) Download the app you want to install on your Mac.
2) In the Downloads folder, double-click to open the installer.
3) In the app installer drag and drop the app in the Applications folder.
4) In the Applications folder, double-click to open the app.
5) In the warning pop-up that opens, click Open.
When Gatekeeper blocks installation of unsigned apps
1) In System Preferences, select Security & Privacy.
2) In the lower pane, in front of the warning that the app was blocked, click Open Anyway.
3) Click Open in the warning pop-up.
4) Click Continue, when you see the installer launched.
Note: You can now follow the steps the installer walks you through like any other app installation.