If you read the help file, it will tell you why it is throwing that error.
autoKrige performs some checks on the coordinate systems of input_data and new_data. If one or both is NA, it is assigned the projection of the other. If they have different projections, an error is raised. If one or both has a non-projected system (i.e. latitude-longitude), an error is raised. This error is raised because 'gstat does use spherical distances when data are in geographical coordinates, however the usual variogram models are typically not non-negative definite on the sphere, and no appropriate models are available' (Edzer Pebesma on r-sig-geo).
It looks like you need to project your data before calling autoKrige
.