Access rights issue when running pipeline build -- newbie!

[John]

Hello I  am new to pipelines in general. I am reading the docs but not sure how to get pass this error in my bitbucket pipeline in the Build stage:

git push -f git@bitbucket.org:<username>/<username>.bitbucket.io.git master 
Warning: Permanently added the RSA host key for IP address '18.205.93.1' to the list of known hosts.Permission denied (publickey).fatal: Could not read from remote repository.Please make sure you have the correct access rights and the repository exists.

I removed my username from the above code for this post.