I got it to work in the end by:
1: Creating a collision channel and object for the goal net, which blocks everything but IGNORES THE GOAL POSTS
2: Creating a collision channel and object for the goal post which blocks everything but IGNORES THE GOAL NET
3: Turning on “Simulate physics” on the goal nets
This resulted in a nice ripple effect when the ball hits, and I will make the material of the net less bouncy (or not bouncy at all) to make the ball not bounce off the back. However for this to work you need a mesh that already has working apex clothing simulation on it, and you need some collision boxes/capsules/spheres in your physics component for the object (in this case the goal net).