If you are experiencing crashes then please try the following:

Force Close & Restart on iOS: Swipe up from the bottom of the screen (or double-press the Home button), find 8 Ball Champions, and swipe it up to close.

Force Close & Restart on Android: Tap the recent apps button (or swipe up and hold), find 8 Ball Champions, and swipe it off the screen to close.

Close Background Apps: It is possible that background apps are interfering with the game or are taking up too much memory space.

Update OS: Make sure your devices operating system is up to date. An older device OS can cause unexpected issues.
 
Redownload the App: It is possible that the App became corrupted during the download process due to varying speeds or interrupted connections. Make sure to link your account so your progress will be saved. After that, you can try to download the app again to see if that fixes the issue.
 
Network Connection: It is possible that you have an unstable network connection. Try changing network connection to see if that solves the issue.
 
Restarting Device: Restarting the device or cleaning the cache could also clear space for the app. Before doing this, please make sure your account is linked to avoid losing progress.