How to download YouTube

if an app have a higher ios requirements that your ios device is running

you will need to Update your iPhone, iPad, or iPod touch - Apple Support

if your ios device say it's allready up to date then it's because it's hardware can't run any higher version and then you can't use the app

The Youtube App requires a higher version of iOS/iPadOS than your iPad can support. The minimum OS requirement for Youtube is iOS12 or later; depending upon your installed version of iOS, you might still be able to access YouTube from your web browser.

Whether or not you are able to update any iPad to a newer version of iOS/iPadOS will be dictated by the iPad model - and the currently installed version of iOS. You can find this information here:

Settings > General > About

Not sure which iPad you have? Identify your iPad model.

Here is a list of the highest version of iOS supported by the older models of iPad (for simplicity - “generations” are shortened to a number) that are restricted in their ability to be updated:

iPad1 - iOS 5.1.1

iPad2, iPad3 and iPad mini1 - iOS 9.3.5 (WiFi Only models), iOS 9.3.6 (WiFi & Cellular)

iPad4 - iOS 10.3.3 (WiFi Only), iOS 10.3.4 (WiFi & Cellular)

iPad Air1, iPad mini2 and iPad mini3 - iOS 12.5.5

Newer models, not appearing in this list, are all able to be updated to the current version, iPadOS 15.4

If you want or need to access to Apps requiring a more recent version of iOS than your iPad is able to support, you’ll need to consider replacement of your iPad with a newer or current model that supports iPadOS15.

Sorry, I appreciate that this may not be what you were hoping to learn.

I hope this information provides clarity as to your available options - and the fundamental limitations of your iPad.