Download latest version from releases tab.
To support colors similar to WotLK (orange/yellow), you need ThreatLib-2.0, which is included in e.g. Omen.
There are no additional settings.
You can configure how the aggro indicator should be displayed in each ElvUI unit frame settings ("Threat Display Mode").
Known issues:
- Icons don't work
- Indicator color (red/orange/yellow) doesn't always work as expected