If everything opens online and doesn’t return any errors, then the archive was definitely packed with the wrong program. I’m using Windows, and WinRar says it needs version “1.0 / Store Unix” to unpack. If the archiver detects everything, it should correctly assemble the archive after unpacking. But if there are errors, especially in the “collection” file, then things are bad. This file is important because it’s essentially an “sqllite” database containing all the card information, excluding any files located nearby. Sometimes, files that are more important than the actual information are saved there.
Therefore, if you’re not very knowledgeable about this, it’s easier to ask a friend to save the deck again as an “apkg” file. If there are errors, there’s a good chance something on their drive is already corrupted, possibly even the Anki program itself. Then you’ll need to figure out why this is happening. Another option is to make the deck public and share it with you, and then they can delete it.