Oiled Longbow string aquisition
You mean the “Machined Longbow String”, right?
I think you have to actually kill the dragon and then loot the chest/pods afterwards. Did you just open pods without actually succeeding the meta?
Here’s an older discussion:
People suggest that you get the other collection items first.
Once you’ve got the collection unlocked (which you do), just do the meta once. You’ll get it from the end chest most probably.