I have been lucky enough to have a friend let me borrow a R5 to try for a few dives. It has this piece so I can use my same fibre optic strobe cords and i'm hoping people can chime in if there's any tips or tricks to using it? Thanks

Presumably this is a Nauticam flash trigger which would be manual only. So set the camera to manual plug it into the hotshoe and turn the trigger on, fire a test shot and check the LEDs flash. The camera shouldn't even know it's there.

Once you have it flashing you should be able to install it in the housing and attach your optic fibre cables and fire away. If it's another brand you might need to do something else, but if you confirm it's Nauticam this is how it should work.