Once the installation is complete, the app icon will appear on your home screen. However, it won't open yet.
Now, you should be able to launch YouTube.
If you don't want to jailbreak, you can sideload the specific Youtube.ipa using a computer. Youtube.ipa For Ios 9.3.5
Because these apps are modified to run on unsupported firmware, things break over time:
Here is the technical hurdle: When a developer (like Google) updates an app to support iOS 14, 15, or 16, they stop supporting older operating systems. However, Apple’s servers remember the last version of the app that worked for iOS 9. Once the installation is complete, the app icon
In theory, if you previously downloaded YouTube on your iPhone 4s years ago, you can go to "Purchased" in the App Store and download the last compatible version (likely YouTube 14.x or 15.x). But if you have a fresh device, or you never downloaded it before, the App Store refuses to give you that old version.
This is why people search for "YouTube.ipa for iOS 9.3.5" — they want the specific file archive of that final compatible version to manually install it. Now, you should be able to launch YouTube
iOS 9.3.5 is an older build of Apple’s mobile operating system (released in 2016). Modern App Store apps and updates are generally built for newer iOS versions, so running the current official YouTube app on a device stuck at iOS 9.3.5 (older iPhone/iPad) can be difficult. Below is a concise, practical guide covering options, risks, and steps you can try.
Apple stopped supporting iOS 9.3.5 years ago. Consequently, Google updated the official YouTube app to require newer iOS versions (iOS 11 or later). If you try to download YouTube from the App Store on an iOS 9 device, it will either tell you the app is incompatible or crash immediately upon launching.
A modded .ipa is a cracked/modified version of an older YouTube app (usually version 12.x or similar) that has been "backported" by developers to trick the app into thinking it is running on a newer operating system.