Try 7-Zip if your on PC, try the Alternate Download mode regardless, and make sure if your downloading on a phone your not trying to unpack a version that was stopped during a data download and the file size is around 1.19 GB,
I’ve downloaded it at least four times from the most recent links using 7-Zip to extract it on Windows 7 (I was having a renpy issue, nothing to do with this game), and the worst case scenario I have come across was when downloading on my phone over data I would sometimes get two copies, one that had never completed the download and one that had restarted with a (1) at the end of the filename so it wouldn’t be considered an archive when I looked at it on Windows in my phone until I copied it and renamed it.
I can assure you it is NOT the actual archive, it is either the program your using to extract it or a failed download.