If you want to have it on 2D HUD, you’ll need to make a custom shader that rotates and pans texture and then use that as HUD material.
Like this:
And then in HUD blueprint you feed this material pitch and roll of your vehicle:
If you want to have attitude indicator as a 3D model in cockpit (like in the example project), it’s much simpler, just rotate the ball in the opposite of your vehicle’s rotation.