Hey @ambikaTewari_ATCI,
Thanks for reaching out!
I am using https://experienceleague.adobe.com/docs/core-services/interface/customer-attributes/crs-data-file.ht... as a reference for the below answers:
1. The '.fin' sends the trigger to ingest 1 file with the same name as '.csv'. If you are dividing one big file into multiple .csvs, then you would have to upload corresponding multiple .fin files. Note that Customer Attributes is designed to handle a few files per day. To mitigate the issue of having a large number of small files delaying processing, files sent within 30 minutes of a previous batch from the same organization are routed to a lower-priority queue.
2. After you upload the .fin file in the Customer Attributes FTP, the system retrieves data quickly (within one minute). This differs from other Adobe FTP-based systems, which pick up data less frequently (around once per hour).
3. The Customer Attributes UI does have a UI which indicates the upload status- if it was successful or if it failed.
Hope this helps, do let us know if you have any questions!