When I try to download certain apps on my iPhone, it says This Item Is Over 50MB?

It also says 'You must connect to a Wi-Fi network or use iTunes on your computer to download it.' I've even turned on the Wi-Fi network on my iPhone & I have attempted to download it on my MacBook. It won't download!

If I'm not mistaken your iPhone is almost out of memory. Sorry i couldn't be of much help.