Anyone is allowed to claim it but:
on Tartaros, there are no consequences for someone stealing your stuff.
on Syndesia, there are consequences if someone steals your stuff, they will get thief mark, which will affect their interaction with some NPCs, and they will become free targets for other people. Perhaps even bounty targets.
on Arboreus (inside safe zone) only you will beable to loot it becuase good alligned player can't steal from other good aligned player, and evil aligned players can't enter safe zone.
on Arboreus outside of safe zone, theft is possible by a demon player IF you are unlucky that you happen to be there at a time some demon is visiting (demons can only stay there 30 minutes at a time).