i think heed might have made one of these and put it in his medeival pack. i think there's like a massive pack of assorted RPG weapons with their own skins that do differing damage that're on RTB and it might have one. I don't think there's one with hand animations, though
For Heedi's Medieval Weapons Pack, there are no animations.
The Recurved Bow, however, probably fits the OP description of a longbow.
Well, it IS a RECURVED Bow, not a LONGBOW, but, close enough.