This usually happens if you forgot to delete the original Pokémon GO app or if you downloaded the wrong architecture (32-bit vs 64-bit) for your phone.
After sideloading, you must always "Trust" the certificate in your iPhone settings before the app will open. Troubleshooting Common Issues 1pogolinks install
Installing via iOS is more complex due to Apple’s security restrictions. Locate the iOS section of the site. Choose an Installation Method: This usually happens if you forgot to delete