can I buy a mac lap top with a military discount using my apple card?

Yes but you won’t be able to get financing on it direct. You still need to go through the ID.me portal or whichever it is there using now. Check out with your applecard. ONCE THE ITEM HAS SHIPPED (that’s when you will be billed) call apple support ask to be connected with an applecard specialist and tell them you want to convert it to monthly installments