The article explains the reason as to why the Event tab is not displaying any Events. The Event tab is used to add organizational events and promotions.
The Event tab feature would manually need to be added to an app via the BiznessApp Console. Have a look at Building the Events v2 Feature for more information.
Users may notice that their past events are not being displayed in the Event tab, as per the image below.
This is by design and happens as events that have already past are not be visible on the Event page.