Which ClientId and ClientSecret are you using in your OAuth credentials. The user 'registration' has no permissions to publish content to the Content Deployer. If you are using the default users and their roles you need to use this user 'cmuser' where the default password is 'CMUserP@ssw0rd'. Please make sure you update these passwords.

You can find the default users and their passwords in the cd_ambient_conf.xml from your discovery service (config folder)