I remember that there where some big changes between iOS 7 and iOS 8. The Reality Editor presently does not support iOS 7. The App Store needs a minimum version of iOS8.0 at this point, when I upload a new version
Beside these two issues, the iPhone 4 is to slow to reliable track AR content and project the Web-Content at the same time.
I am sorry but the iPhone 4 is not supported.
Do you have access to any of these devices that can run iOS8:
iPhone 4S (the reality editor will run very slow)
iPhone 6 Plus
iPad 2 (the reality editor will run very slow)
iPad Mini 2
iPod Touch 5G