Aufbau principle does not give correct arrangement of filling up of atomic orbitals in :

According to the Aufbau Principle, an electron enters the orbital with the lowest energy initially in the ground state of an atom, and following electrons are supplied in the order of increasing energies.
A neutral element's total number of electrons is represented by its electronic configuration. To get the total number of electrons in an atom, we add all the superscripts.

$\begin{array}{r}Cr:24:1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}3d^5\\ Cu:29:1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}3d^{10}\end{array}$