When enrolling your devices, you only need to enroll one node: The Juniper ATP Cloud automatically recognizes the HA configuration and applies the same license and configuration to both nodes of the cluster.
You must use the same license key on both cluster nodes: The HA cluster needs to share the same license key in order to be recognized as a single device by the Juniper ATP Cloud.
You must set up your HA cluster before enrolling your devices with Juniper ATP Cloud. And it is not necessary to use different license keys on both cluster nodes because the HA cluster shares the same license key.
The two statements that are correct in this scenario are:
When enrolling your devices, you only need to enroll one node. This is because the Juniper ATP Cloud service supports chassis cluster mode for SRX Series devices. When you enroll a chassis cluster, you only need to enroll the primary node of the cluster. The secondary node will be automatically enrolled and synchronized with the primary node. You do not need to enroll the secondary node separately or perform any additional configuration on it.
You must use the same license key on both cluster nodes. This is because the Juniper ATP Cloud service requires a license key to activate the service on the SRX Series devices. The license key is tied to the serial number of the device. When you enroll a chassis cluster, you must use the same license key on both nodes of the cluster. The license key must match the serial number of the primary node of the cluster. You cannot use different license keys on the cluster nodes.