If your app fails to install, or fails to run, we can suggest a few troubleshooting steps. 

First, you may try taking the same exact app bundle you uploaded and run in locally on the iOS Simulator directly. 

You can try this by taking the same .zip file you upload to Appetize, unzipping it to get the .app bundle, and then installing onto a running iOS Simulator with the command:
xcrun simctl install booted <your bundle name>.app/

Even if that works, you might also try doing the same on another developer's machine. Sometimes the .app bundle includes references to local files that were not properly added to the bundle, so it will work on the same developer's machine, but not another. 

Second, if your app installs, but just encounters a crash, you may enable our debug log to check for the unhandled exception or other error that caused the crash. 

Please note that these debug logs can often include some "red herrings" or other misleading clues. Try to look for unhandled exceptions or similar! 

Happy digging!