Sorry, but it doesn't seems like I can just fix that for you that easily. Playstation and XInput gamepads use different axis configurations in Unity. You can check out how this works here: https://wiki.unity3d.com/index.php/Xbox360Controller
- The triggers are axis 3.
- The right stick are axis 4 (horizontal) and 5 (vertical).
So people with an XInput gamepads like me just need to hold the right stick down when they don't want to shoot.
I don't think there is a simple fix to just make it work on either gamepad. I think you have to add some way for the player to tell you what gamepad they have and configure the control accordingly. Or perhaps switching to the new Unity Input System might help?