With that amount of polygons your retopo could be a lot better and follow the shapes of the highpoly a lot closer instead of being just a blob of polygons. Regarding the bake, are you using a cage in Xnormal and have you made sure the objects are in the same location? as it seems to be baking something it could be that the…
This looks like the scale and/or position of your highpoly and low poly meshes don't match. Check xNormal's 3D viewer to verify, or bake in an app like Toolbag or Knald so you're not flying blind. It also looks like your low poly mesh normals aren't set up well. I would recommend finding some basic tutorials on normal…