Push and Live notifications are two different things on desktop. Live notifications happen when your browser is open to a Discourse tab, and are included by default. Users just need to enable them in their personal preferences (they’re also asked with a banner at some point).
Push notifications are received even when your browser is closed. This requires a plugin: Discourse Push Notifications for Desktop, which has some more settings… there’s a site setting called desktop push notifications enabled. Once that’s enabled users can prefer push notifications on their profile under “Live Notifications” (https://meta.discourse.org/my/preferences/notifications).
