Ionic compound AlCl3 consists of Al3+ and Cl- that come together in a 1:3 ratio to form a neutral salt.
The electronic configurations of the elements are not the configurations in the compound if it is made up of ions: The configurations of the representative elements as ions are the configurations of the nearest noble gases
Al: 1s22s22p63s23p1 Al3+: 1s22s22p6 or [Ne]
Cl: 1s22s22p63s23p5 Cl-: 1s22s22p63s23p6 or [Ar]
Hope that clarifies things.