PC, Mac, Linux, Android?
Assuming Android... Check that you have enough space to install the APK.
Android being Android and Android being weird, you most likely need from 2 to 4 times the size of the APK, so at least 4GB of free space to properly install the APK.
You can backup your saves by going to this route with a file explorer:
Android/data/com.domain.corruptedkingdoms/saves
You will probably need a file explorer like SolidExplorer if you're on android 10 and after.
After making a backup of your saves you can uninstall the app, install the new version and move the saves back where they belong.