Firstly, please accept our apologies for this inconvenience. We suggest that you make sure that the app on your device is up to date. If it is, uninstalling and downloading the app again should fix the issue. We have a small guide on how to do so in our Can I play in the mobile browser, or do I need to download an app? article.
If the above does not work, please take a screenshot of any errors you may find to be able to send to our Customer Support.