thanks everyone for all the help before.
This time, I needed the Execution Window in order to see what the code is doing, but it doesn't open. Trying to open it gives me the dialog box you see below, and it simply never opens. I'm running the Ubuntu app on my Windows 10 laptop, utilizing the Linux Subsystem. DDD opens with VcXsrv that I downloaded in order to display the debugger. I'm not sure what's wrong, haven't seen this issue anywhere else when I search for it. Is it an issue with VcXsrv? It can display multiple windows from what I've seen (opening several DDD debuggers).
Any advice is appreciated, thanks!
Alright, I was being mentally incapable. Linux isn't my strong suit, I needed to install xterm apparently:
sudo apt-get install xterm
That solved the issue.