in the code you originally posted, it appears library defines the fingerprint array in the .h file allowing it to be modified by the user of the library. the drawback of this is that the fingerprint array gets duplicated in every file including the .h. no harm but wasteful.
in the code you posted in reply #8, the fingerprint array is defined inside setup() and is therefore not accessible outside that function.
the code should at least compile if the definition is moved outside of setup().
don't see any code for updating the fingerprint array