I need your help in rigging... 

The metarig you're using has IK (inverse kinematics) constraints, you will have to manually create those for the additional bones of the wing.

Hi; this Wing Folding issue can be solved in Blender with, for example, Action Bone Constraint(s), to the Wing Bone(s). Basically, it is as if you were creating a sequence of arbitrary motions/Transforms, which are Key-Framed and decided by the rigger but which make part of a special Action; this whole Action then is set to be triggered, only, by the Action Bone Constraint. The technique is a bit complicated, but it is effective and fortunately there exist a few good tutorials on that subect on RU-vid already. Because it is a Skeleton-based method, all the motions in the animations can Baked and then Exported.

you could use transformation constraints so the wings fold the way you want to

i haven't used blender at all but i think that it doesn't work because the wings are models, i think they need some kind of modifier to fold the or shrink the wings when arms are closed.