hi, you have to use the setVelocity() function each time you want to set it (at the end of each if (Sup.Input.isKeyDown)
this.actor.arcadeBody2D.setVelocityX(velocity.x);
without it, your actor doesn't know it will have to move.
don't forget that if you release your finger from the key, your actor should stop, so in your else (for idle position) under the line
this.actor.spriteRenderer.setAnimation(this.currentIdle);
set the velocity to 0.
this.actor.arcadeBody2D.setVelocityX(0);
Hope it helps ;)