If you know the steps to set up notifications on any flavour of Linux please contact me with as many details as you can give. Thanks!
You can test to make sure notifications are coming through with the browser notification tester.
Wayland is the default display server for most Linux flavours now, but Brave Rewards notifications do not work under Wayland. However normal notifications from sites do work, so even if you see a notification with the browser notification tester you likely will not receive ad notifications.