Dear Pooja,
As already explained to you earlier, a person can directly be appointed as MD at general meeting after following the procedure given in sec 197 read with schedule V. There is no need for him to be additional directly. However, Notice calling General Meeting should contain a special resolution in this regard.
However, in your case, as the agm is already done and it is a listed company, you can normalize the transaction by appointing him as Additional Director and designate him as Managing Director and confirm his appointment at the ensuing AGM. I am enclosing herewith extract of our CSP module for your reference.