Go to > Linked Devices > Link a Device and scan the QR code on your iPad screen. Turning it into a "Portable App":

Download or Puffin Web Browser from the iOS App Store. (If you cannot download them, see the App Store trick below). Open the browser and access the settings menu.

Find a trusted archive repository to download a legacy wrapper built for iOS 9. Connect your iPad 2 to the computer via a 30-pin USB cable. Drag the .ipa file into Sideloadly. Enter your Apple ID to sign the app. Click Start to install it onto your iPad 2.