Can I use the topic operator on a Kafka already installed without using Strimzi/Operator?

[SebTardif]

How do I define the information about that existing cluster so that the topic operator knows what to do?

[scholzj]

The Topic Operator deployment has environment variables on to configure the connection to the Kafka cluster (you can check the docs => the standalone topic operator installation for more details). And the topics are created in this cluster.