First, try restarting the game and your phone. Check your internet connection and phone storage.
Then check if there are any updates for the game itself or for your phone's operating system and install them.
If that doesn't help, clear the game's cache (in the app settings) or reinstall it (don't forget to link your account to your social media profile beforehand so you don't lose your progress).
If it still crashes, contact support. Specify your phone model, system version, and what exactly is happening. Screenshots or videos will be very helpful. We will try to help you. To write to us, click on the icon in the lower right corner.