Alright, so you have downloaded the .zip file, before you can install the .apk file, you need to extract the .zip first. You can not install the .apk if it's still compressed in the .zip
Sounds like there's an issue with the app on your phone that handles extracting compressed files. I suggest either trying a different app from the app store to extract the .zip or you can hop into my discord and I'll upload the raw .apk file there.