Our React Native UI Kit does not work with Expo GO since it requires some custom native modules. Also, expo does not recommend using Expo GO for building production grade apps. So in order to use our UI Kit in an expo app you need to use development builds. You can follow this official Expo guide for more details. The UI Kit requires a few permissions to run so you need to make some changes in your app.json file. 
"ios": {
  "infoPlist": {
    "NSCameraUsageDescription": "This is for Camera permission",
    "NSMicrophoneUsageDescription": "This is for Microphone permission"
  }
},
"android": {
  "permissions": [
    "android.permission.INTERNET",
    "android.permission.CAMERA",
    "android.permission.MODIFY_AUDIO_SETTINGS",
    "android.permission.RECORD_AUDIO",
    "android.permission.ACCESS_NETWORK_STATE"
  ]
},
For a reference implementation, check out the CometChat React Native SampleAppExpo for reference