Redundant Interfaces

This is my first Firewall Setup and my first post here so forgive me if this post is a little hard to follow

Here is my setup:

2 Fortigate 500D's in a HA Active\Passive

2 ISPs

each connected to a  switch (ISP1-->Sw1   ISP2---> SW2) by a single interface with the switches connected via crossover

The Switches are not stacked

SD-WAN

2 Redundant Connections WAN1(port1, port 2) WAN2(port3 ,port4)

My question:

Can I connect each individual port of the redundant interface to a separate switch

Port1--> Sw1(port1)  Port2-->SW2(port1)

or

do I have to create aggregate ports on the switches and connect both ports of the redundant interface to the aggregate ports on a single switch?

WAN1\Port1-->Sw1\port1

WAN1\Port2-->SW1\port2

Thank you