"If the preferred role is Primary, then this unit becomes the primary unit if it is configured first in a new HA cluster. If there is an existing primary unit, then this unit becomes a secondary unit." (https://docs.fortinet.com/document/fortianalyzer/7.0.5/administration-guide/275104)

In order to configure IOC, you require the following:
* A one-year subscription to IOC. Note that FortiAnalyzer does include an evaluation license, but it is restrictive and only meant to give you an idea of how the feature works.
* A web filter services subscription on FortiGate device(s)
* Web filter policies on FortiGate device(s) that send traffic to FortiAnalyzer Compromised Hosts or Indicators of Compromise service (IOC) is a licensed feature.
To view Compromised Hosts, you must turn on the UTM web filter of FortiGate devices and subscribe your FortiAnalyzer unit to FortiGuard to keep its local threat database synchronized with the FortiGuard threat database. See Subscribing FortiAnalyzer to FortiGuard.
Ref : https://docs.fortinet.com/document/fortianalyzer/6.4.0/administration-guide/137635/viewing-compromised-hosts

https://docs.fortinet.com/document/fortianalyzer/6.2.5/cli-reference/849211/global