Need an advice to link FG-40F with the FortiSwitch

[ZhekA]

Hey folks, 

Would appreciate your advice guiding me to do what I mentioned in the subject.

There's S108E-POE FortiSwitch connected to the FG-40F firewall port labeled as fortilink. In firewall GUI it is labeled as "a" interface. The switch runs 3.06.x firmware. All ports are active/green and I'm confused what to do next. 

I assume I don't need to create yet another FortiLink interface under WiFi & Switch controller ?

And also I don't see any discovered switches under "Managed FortiSwitch". How would I make the firewall to discover the switch ? Or it is not compatible with FG-40F ? 

[SecurityPlus]

What FortiOS is the firewall running. Can you double-check the FortiSwitch firmware. 3.06.x firmware seems as though it is very old.