I officially have the Unable to Verify error on my iPhone. What next?

I have the Unable to verify app error. It says an internet connection is required even though I have three bars of Wi-Fi and I’m not using cellular data. Plus, the app I’ve been trying to install, I’ve deleted and installed multiple times.. but it still won’t work. I have made sure that I have verified the app in settings, but nothing works. What do I do now?