Q: Can't find tab to load Airplay in App Store

airplay is built into ios 7.  there is no airplay in the app store.  you can find the airplay icon in control center when you swipe up.  Note, the icon will only appear if it sees another airplay device on the same network with the same apple id, and when home sharing is enabled on both devices and on your computer - i tunes.

Airplay is not an app:  it is part of iOS, and you find it in the Control Centre on your iPad.

http://support.apple.com/kb/HT4437