The setup of fingers is not obligatory and it is only necessary in cases when you need to capture hand animations. Press Fingers button that is under the name of Skeletal Mesh to move to open fingers setup tab.
It is necessary to specify the following info for each finger of both hands:
To determine this axis, press Eye button that is to the right of the hand name.
In figure above, the y-axis is pointed to the outside. If it were pointing downwards, one had to specify “Y-” in parameter settings.