The incubator project CB Queries can execute database queries on internal and external database tables. This means you could use it to synchronize profile data to any number of databases after registration and after profile update triggers for example. If you need to execute APIs to implement the user you could use the integration CB Code, which does the same thing except performs GET, POST, or XML requests on URLs (can pass profile data).

Incubator projects don't come with documentation, but are well commented. Once installed click "CB Queries" within CB > Plugin Management to access its backend. Once there just create a new query selecting what triggers you'd like, leaving user on automatic, and setting access to everybody. From there just formulate your database query as necessary and configure if internal or external. You can imply our installation services from your Membership tab on your Joomlapolis profile, but that's a heavy price tag for 1 plugin; recommend you attempting to tackle configuring this first (the knowledge of knowing how would be invaluable in your future sites).