Bitbucket Pipelines : Permission denied (publickey)

I am new to Bitbucket pipelines, and trying to setup with salesforce. I am getting the following issue. Can anyone help me to resolve this issue? I did follow the instructions provided in the document to generate public key, still I am having this issue.

https://confluence.atlassian.com/bitbucket/access-remote-hosts-via-ssh-847452940.html