Hi!
The Paper2D not support Notify system like in Persona. But you can add sound your self.
I use Paper2D template for this example.
Open Paper Flipbook RunningAnimation. We need frames 7 and 15.
Open a blueprint 2DSideScrollerCharacter and add these nodes. I captured events of footsteps from the flipbook, using Get Playback Position in Frame node.
Open Sound Cue and set Max Concurrent Resolution Rule to Stop Oldest
This is result. Bad sound is a problem of the screen capture program.