When BeauByte has a grey icon and says that it's waiting to download, normally the app will quickly resume downloading and installing on your device. But sometimes the app stalls and never progresses. Usually this is due to a connection problem with the App Store or some other issue with your device.
The easiest way to correct the problem is to restart your iPhone. When the iPhone reboots, the app should continue to load and install normally, assuming your cellular data or Wi-Fi connection is working properly.