please make sure to read our doc here, specifically for secure clusters.
Also consider that CDP 7.1.1 is not supported, as stated here. It might work, however.
As you will see from the documentation I posted above, DSS will need to be configured to access the cluster by running the hadoop integration and spark integration.
Once done, DSS should be able to offload jobs to the cluster.
To do so you don't need to integrate with Livy. What you need to do is map users and groups to hadoop users, as you want to run all your activities (in hadoop) as serviceA. This is done in Administration -> Settings -> Login (LDAP, SSO) -> User Isolation.
This feature is only available in Enterprise license.
Architect @ Dataiku