Guest Wi-Fi Access with forti AP

Hello Everybody,

As a total Newbie, I need some help. I'm the network administrator of a little association. We have an Active directory.  There is wi-fi access to our network (and through it to the internet) for some workers. For that we use 3 Forti AP 221C.

Of course I have access to their admin page through a web browser and also to lots of setting through forticloud.

I would like to set up a Guest WiFi access that only give access to the internet (not to shared folder on our LAN for example).

Is it possible ? May I add something else on my network (hardware / software) to do this ? I found this : https://cookbook.fortinet.com/guest-wifi-accounts-60/ but don't know where can I find all this.

Thanks a lot ! Have a Happy New Year !