Connecting G-RAID Thunderbolt 3 to an iMac with Thunderbolt 2

Trying to connect an older iMac with T2 to my new T3 G-RAID. As I don’t have T3 on the iMac I have connected the USB-C out on the G-RAID to a USB on the iMac but I don’t seem to be able to configure the G-RAID as JBOD which is what I want to do. Do I need to get an T3-T2 adapter and connect to one of the T3s on the G-RAID? If so what is the USB-C on the G-RAID for? Thanks!

So now I have connected to the T3 on the G-RAID to the T2 on my iMac using an adapter. The G-RAID won’t allow me to configure as JBOD. It seems to only want to allow RAID 0 or 1 which is not what I want. Any suggestions as to how I can proceed?

Further…

I gave up on the G-RAID utility.
In disk utility both drives were showing up as HGST HUS728…
I selected each one and erased it. Now both drives are showing up on my desktop. And in disk utility each drive is showing as an indented volume of HGST etc.
Does this mean that I am done and that these are now set up as JBOD?

If you see both drives then yes it is in JBOD mode.