So I have the right cable now and I can download dives from my computer into subsurface.
A couple of things:
1) I have six dives in the computer, but only the first 5 show in subsurface.
2) There is no pressure information shown in subsurface.
I'll look at these issues some more, I am not sure if it is libdivecomputer, subsurface, or the computer that is the issue.
Philip