The step will download all your files you uploaded in the GENERIC FILE STORAGE section of the Code Signing tab in your Workflow Editor.
The step will download all your files you uploaded in the GENERIC FILE STORAGE section of the Code Signing tab in your Workflow Editor with the same name, under $GENERIC_FILE_STORAGE path.
As an example, if you upload myconfig.ini to GENERIC FILE STORAGE, then the step will download it and it will be available as $GENERIC_FILE_STORAGE/myconfig.ini