Any enters-the-battlefield abilities of the copied creature trigger when the creature tokens enter the battlefield. The creature tokens also have any “this enters the battlefield with” or “as this enters the battlefield” abilities that the copied creature has.

If Followed Footsteps moves after it has triggered, you get a copy of the newly-enchanted creature.

If Followed Footsteps and the enchanted creature leave the battlefield simultaneously (say via Upheaval or Akroma’s Vengence somehow cast in response to the triggered ability), then a token copy of the creature that was enchanted when it was last on the battlefield is created. If Followed Foosteps did not enchant a creature when last on the battlefield as it went to the graveyard as an SBA when the enchanted creature left the battlefield in response to the trigger, then no copy will get created.