With Slack, you can choose to have notifications fly across the screen - akin to when a phone call comes in, or message - or you can have a more quieter, less intrusive note. To turn on notifications on a Mac running Catalina, open System Preferences, and then find Notifications. But certain features seemed to disappear. Users also got Sidecar, a way to turn an iPad into a second screen. Gone are systems including iTunes, and new features are now in its place like Apple Podcasts and Apple TV.
For those who want to get those alerts up and running again, here's how to get started. But Apple's long time privacy stance has, in some cases, defaulted to turning these off. Typically, red icons show up on the icon that sits in the dock at the bottom of the home screen for Mac users. Catalina, the newest operating system from Apple, has been buggy for many - and Slack users may have noticed badges not alerting them to new messages.