We're sorry to hear that! Are you downloading using the itch.io app? I know it's also possible to download using a web browser but we don't recommend that for the problems that you're seeing!
If you are using the itch.io app and are still having problems, could we please ask that you report the issue you're having here? We don't have any control over downloads - but we want all of our customers to be able to enjoy playing our games!