The IGNxxx_exportgroup data set is created and stored in the workspace (diagram) folder if a user selects Create Grouping Data=Yes. This is No by default.
You can only import one grouping definition at a time so if you have multiple export tables, you need to create a master table containing all grouping definitions prior to import.
To import, set Import Grouping Data property to Yes as well as map the imported grouping table to the Import Dataset option.