Usually this sort of thing means that your system isn’t compatible (doesn’t meet the minimum requirements). So, with this in mind, what are the specs for what you’re playing on?
If you do meet the min requirements and that’s not the issue, it could merely be a problem with the apk itself. Maybe it was interrupted during the download, or a file just, for whatever reason, decided to get corrupted.
In which case I would suggest doing a full reinstall of the game. So long as you’re connected via Facebook or Google Play/ the iOS equivalent, your progress will be fine and load when you open the game again and connect.
If that fails to do the job, I would suggest writing in to support. You can reach them through the in-game channels, or, if you prefer, you could email them at firstname.lastname@example.org. Good luck, and I hope it gets resolved soon!