Yes, You can use same Zookeeper cluster for both Incorta HA and Spark Cluster. You don't need to install separate Zookeeper clusters.
1. Add the following line to conf/spark-env.sh and pass zookeeper cluster nodes. I have used sample zoo-1,2,3.
export SPARK_DAEMON_JAVA_OPTS="-Dspark.deploy.recoveryMode=ZOOKEEPER -Dspark.deploy.zookeeper.url=zoo-1:2181,zoo-2:2181,zoo-3:2181"