"Calculations returned the following error message: A polygon with inner or outer rings was found. Polygons with multiple rings are not supported by this version of LoadBuilder."
The standalone versions of WaterGEMS and WaterCAD do not support complex polygons. In order to use complex polygons you will have to use WaterGEMS in the ArcGIS environment.
How do each of the Loadbuilder methods work?
Troubleshooting and Understanding LoadBuilder
Opening a Hydraulic Model in the ArcMap (ArcGIS) platform for the first time