There is no metadata to add for this. Your mongo service runs the official mongo:8.0 image with no custom start command, and both of those meet the MongoDB High Availability prerequisites. When a service qualifies, the High Availability section is reached from Database → Config → High Availability.

The service was created directly from that image rather than from our MongoDB template, and from what we can read we have not established why the Database tab is missing for it.

Could you share a screenshot of the service's open panel showing the tabs you see, along with the environment you're viewing it in?