Hi Chinna,
Microsoft.BizTalk.Adapter.SftpInvoker.SftpException: Open SFTP connection error error doesnt help us (either you) much. It says there is a error while opening a SFTP connection. There many blocks which makes the proper end to end connection using SFTP. As suggested ensure you can connect using a tool FileZilla Client
https://filezilla-project.org/download.php
FileZilla is a simple tool to use. Once you have confirmed that your connection works with your configuration, try to connect your server using BizTalk SFTP adapter.