If you downloaded Away Messages and it doesn’t show up on your home screen, then you just need to enable it your Message App settings. This is a Message App which is a new type of app introduced in iOS10, they only appear in the iOS Message client, not on your home screen. This has nothing to do with the app developer, its just how Apple manages the Message apps. Follow the guide below to enable/find it:
1.) Open your iOS Messagse client
2.) Open a conversation
3.) Tap the App List Icon
4.) If you see a screen similar to the below image, go to step 6, otherwise go to step 5. Or if you see Away here, you are done just tap the icon.
5.) Tap the Apps Icon in the lower left corner to bring up the App List
6.) Tap the store button
7.) Tap the manage button
8.) Toggle “Away” on, toggle switch should be green
9.) Now go back to step 4 or 6 and tap the “Away” icon to open the app!