IPA file not downloading, stuck on "waiting"

Hello! so, I imported an .IPA file onto my old iPad Air 2 in an attempt to download a game that is no longer on the App Store ("Escape to Plastic Beach" if it matters), and the app icon is appearing on the screen, but it just says "Waiting..." instead of downloading. I've tapped it, and tried to reinstall countless times, to no avail. My current iPad version is 9.3.5, and the game went off the App Store in 2014. So that could be a component as to why it won't download. But I don't know, I'm not too educated in this stuff. Thanks for your help!