How to group notifications by App?
To group notifications
1. Open the Bigin app on your Mac.
2. Click Bigin in the menu bar that runs along the top of the screen.
3. Select Preferences in the dropdown to open Settings in Bigin.
Under General, you can find the title Notifications.
4. Click on Notifications > Notification Grouping.
5. Select By App.

Notifications from the app will now be grouped, and you can view real-time changes to notification grouping in the preview window.