Password dialog for ssh key not working
If it asks for password it means you have not everything properly setup.

You need to set a policy in AWS IAM that grants access to your user to CodeCommit repos. In that policy you need to indicate the resource (repo) ARN (Amazon Resource Name) you want to grant access or * for all of them.

Then you need to generate a SSH key using ssh-keygen and enter the contents of that key (the .pub) in the IAM Console section named IAMUsersSSHKeys.

If you need further help let me know.