It is a simple process to export the Children Units of packages into an Excel file from a campaign:
First, ensure that the packages present on the campaign have Children Units. You can double-check by clicking on the desired package to pull up the package modal, and then navigate to Edit Package. Children Units will be shown within the Children Units tab of the edit package modal.
Once set, then navigate to the Export dropdown and click on the option for Children Report (under Other).
This will generate an Excel export of the Children Units at a campaign level. This means that if there are multiple packages with Children Units, all Children Units will be shown within the export.