Hello! We haven't gotten this report before so it might be something on your end. Which version of Windows are you running? And are you downloading this through your browser or the Itchio app?
No worries!
If you are using Linux, are you able to open other .zip files? If you are unable to open other .zip files, there might be an error with your unzipping software or your system doesn't have one installed by standard.
Let us know if just our .zip is an issue though, we will try to upload another format!
As for your phone, it might be because your settings don't allow apps from outside of the Play Store to be installed. To change this, you can try checking the following:
1. Go to settings on your device
2. Scroll down & Click on Applications
3. Check the box of “Unknown sources to allow installation of non Market Applications”
The exact wording might differ a bit from Android to Android, but we hope that helps!