How to downlad attachment From xml API

How to downlad attachment From xml API

I have the link for the attachment for example this:

https://creatorexport.zoho.com/NULL/claim-
form/Aeroshop_Refund_Form_Report/2729692000000788007/Attachments.File_upload/download/1433869617150_Aut_credito_cuenta.pdf

I know that in the url the word null needs to be replaced by the userName but when i want to download this file this path ask me for a user and password ..

The question is any chance to send the userName and password into the URL by parameter and download the file?


I will like to know how, any question to this email: ecarvajal@aeropost.com

Thanks;