In short, you need an AP to book the AP rate.
It has always been the case that you had to have an AP to book online with AP rate, but it also used to be possible to book an AP rate via phone before actually buying, but then you had to show the AP at check-in/within24hours of arriving or else your booking would revert to full rack rate. I don't know if WDW still makes that allowance, because it is now easy to buy an AP online.
One thing you may want to consider is buying just ONE AP to get the room and other discounts. The lead guest - the person who books the hotel has to have an AP, but the rest of your family can have regular park tickets. Only the AP holder gets the extra perks, but if you stay together that's no big deal as long as AP holder buys everything.
Also, it might make sense to let current AP expire, then buy an all new AP for your trip. It would cost full price, but then your new AP would extend a full year from first use, and be worthwhile if you plan to visit about once a year, AND can manage to book a 2nd trip just before that AP expires.