Do I need the security plus license to do HA with two 5520's?
I was told by our purchasing department that the 5520 was supposed to be able to do HA out of the box, but when I look I see only the VPN + license. Does that mean I can download the security plus license? Or do I even need it on the 5520.
You're thinking of the security plus license that comes with the 5510. The 5520 is able to do failover out of the box. You should be able to verify this by doing a show version and looking for failover.