Piracy: ꜱᴀɪʟ ᴛʜᴇ ʜɪɢʜ ꜱᴇᴀꜱ

Hi, I'm a bit embarrassed to be making such a simple post, but I was hoping someone who's used Anna's Archive before might be able to tell me if I'm making a simple mistake somewhere. I'm trying to get a copy of a textbook for a friend, and it is showing on AA, but when I download the file, it comes without any file type. AA is listing it as a PDF so I tried just adding the extension but no dice. After that I found a reddit post suggesting a similar issue from just 3 days ago, and they had tried uploading the file to chat GPT and were able to get it to repair the file partially. I tried that same and got the same result, it fixed the first 200 or so pages, but nothing after that. AA is indicating that they scraped the file from Internet Archive, but searching for the file on there isn't giving any results so I can't get it directly from IA. I would just assume it's a booked file (which it very well might be) but the fact that the first 200 pages were recoverable makes me think it might still be in there somehow. If at all possible could anyone with experience using AA advise? (Also I'm specifically leaving out the title because I don't want to break any rules, and to be clear, I'm not looking for someone to download it for me, just trying to understand if I'm doing something wrong)