Fortigate 60E running on 7.2.4 and three 221E access points running on 7.2. The switches are not from Fortinet.
How I set it up so far:
Since it should be a wired network too, I took a physical interface for this and set Security Mode to Captive Portal:
The interface is connected to a new VLAN. I created a new SSID with the VLAN ID, made sure that the VLAN is tagged on the correct ports and modified the disclaimer page.
I don't think a "hotspot" style password is possible with the native FortiGate captive portal. You should look at FortiAuthenticator instead, which supports much more rich captive portals. Or another NAC solution like Aruba ClearPass or Cisco ISE (both of which also support hotspot passwords).
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