I can't seem to download my ATT, pls help

Hi, here I am again asking your kind hearts as to illuminate me if what I'm experiencing in downloading my ATT normal. I received my ATT yesterday and I can't seem to download it. I have adobe reader installed in my computer. I tried to transfer it to my documents but it cannot be opened, it said, the file is damaged or improperly decoded. I am concerned because it's the first time that happened. Whenever I download an attachment, it will just take a couple of minutes to download. As I tried to download it, it's just transferring data, no time given to finish, after an hour I checked it but it still transferring data, is it normal? I just cancelled it and still hasn't downloaded my ATT.