Never download modified .ipa files from unverified online repositories or "tweaked" app stores. These frequently contain hidden malware or data loggers.
This occurs because iOS blocks unsigned enterprise apps by default. Navigate to > General > VPN & Device Management and explicitly trust the developer profile. App Crashes on Launch
Go to Settings > General > iPhone Storage and offload unused apps to free up the required space.
Go to your iPhone's > Profile Downloaded and tap Install in the top-right corner.
If you are looking for official training tools from the source, you should use the official applications: