Transparent Split mode

Hello All...This is our first Red (Red 15) and we need to set it up in Transparent Split mode because their existing Cisco router needs to handle the network security for their network.  Forgive me if this is very basic but for the life of me I can not see anywhere how this unit is supposed to be cabled when in transparent split mode.  It has LAN ports as well as a WAN port but in this configuration I have no idea how it is supposed to be cabled.

So I built out the profile on the corporate XG and it registered with the RED cloud service.  I then plugged the Red into the Remote LAN switch via the LAN port on the Red.  It did go out and register itself and it shows online.  It got an IP on the internal remote network.  I then built a static route on the Remote Cisco to route traffic destined for the corp HQ to point to the IP of the RED.  No luck routing traffic.

So (again this seems basic) but do I need to plug anything into the WAN port?  For instance, does it need to have a second public IP address?  It seems like that route go against what I have been reading about RED's but perhaps it does? 

Anyway, thanks for any input as I am very confused on this one.

Thanks

Dave