Looking at the photo of the case from the rear, you can see that the Rpi header is occupied by a board with a connector coming from it. That is where you need to install the DRAWS board.

I have not made any cables. You probably got yours from Art Miller or Robert Sears. I think it is safe to assume that if the cable worked on your UDRC it is going to work on the DRAWS. Most of us are

Whatcom county is doing something very interesting to solve these problems and it works very well on a Rpi with a UDRC controller. We are using Fldigi with Flmsg running MT-63 2000L on VHF. Flmsg supp

If you have a keyboard, hold down the [ALT] key and then drag from anywhere in the window with your mouse of you finger on the screen. Budd WB7FHC