IDN aggregation will always fail if the column headers don’t align with the schema. Unfortunately the error isn’t very descriptive to this issue, but using the “Upload Schema” option you can overwrite the schema without doing it manually field by field. The obvious downside - be sure you want to do this before just updating it.
I’ve seen HR change file formats without communication both intentionally and accidently so knowing what the format should be is critical to knowing if the schema should be changed.