iOS doesn't allow browser push notifications so iPhone/iPad users can only get push notifications using the native app. Those who use Chrome, Firefox or Safari on MacOS will be able to use Browser Push Notifications.
Click on the "Enable Push Notifications for this Browser" link at the top of the notifications box on your Dashboard. This will open up a window which will prompt you to enable notifications for your browser. Once enabled, you can turn them off/on from your My Account page. You will receive notifications for events configured in the Communication Options.