ArcRORB is not compatible with ArcGIS Pro. In general, add-ins developed for ArcMap don’t support ArcGIS Pro because ArcGIS Pro is a complete re-implementation of ArcMap, so add-ins made for one must be completely remade to support the other.
We currently have no plans to support ArcGIS Pro. It would be a significant amount of effort to remake the plugin in the new environment. If, at some point, the appetite for an ArcGIS Pro version increased we may consider it, but we would have to find the right partner to commercially support this.