Attempting to create a custom location type using Esri Maps for Office fails with the message:
"An error has occurred."
This happens in the Add Location Type wizard upon naming a location and clicking the Add button.
Add Location Type wizard
The cause of this error is insufficient read / write permissions for the EsriMaps folder where the new location type is written.
The following are the default installation locations of the EsriMaps folder. If another location was chosen during installation, change access permissions there.