SFTP and HTTP_AAE issue

We have a situation in which we send/receive files to our partner via SFTP. Receiving the files via SFTP is always sucessful. However, sending them files via SFTP always yields an AUTH failed error. As such, we decided to implement the HTTP_AAE adapter using the POST Message Protocol. we are able to see a successful message in PI, but the partner claims they never receive the payload. We are sending them a text file. I have a feeling that I may be missing certain parameters but am not sure. Here are my screenshots from config.