Forticonnect Vs FortiAuthenticator

Hi, a couple of days ago, I was tasked with a FortiAuthenticator deplpoyment.

While doing my research, I came across the FortiConnect appliance, which seemed to share much of the same functionality. So,I'm left kind of confused as to what appliance to choose.

The intent is as follows;

Provide a Aruba Clearpass alternative to run parallel with a Fortinet appliance to better extend the already deployed FortiWLC.

What fortinet appliances would be recommended for such a scenario?

Any advice would be appreciated.