You'll need to download all the extra files and install them appropriately. downloads.php?d=260 That also lists how to do it. Only install the ones you need from the errors you get (if thats what you're getting) Also make sure that your internet security isn't blocking AU from connecting to the internet. that can cause some authorization problems as far as I know?
Like I said.. check to ensure that your internet security isn't blocking it. Other than that, try PMing a mod about it. (or Expon himself, however you probably won't get a reply from him for a while!) Oh and make sure you're logging in using your neofriends account first XD I made that mistake first time I tried. Even though it clearly says NF's login and neopets login..
All your questions have been answered in this thread: program-discussion-f88/acheteur-ultime-4-95-t27205.html Read through it. THEN if you have any questions post on that thread.
Locked As Junior pointed out, all questions about AU can be asked/answered in the following thread: program-discussion-f88/acheteur-ultime-4-95-t27205.html