Hello R D,
Refer below blogs:
Condition Master Data - Customizing Download
Condition Master Data Download
If you have successfully downloaded DNL_CUST_CNDALL, then you can go ahead with master data download.
You can check transaction R3AC5 in CRM to know the actual object name.
If its a custom table ( table number >= 501), then you need to create a new adapter object by copying an existing object and by changing the table name under the tab 'Tables/Structures' in R3AC5.
If you can let me know tabe table name in ECC, I can provide more details if you are unable to
proceed further with above hints.
Best Regards,
Shanthala.