I'm currently running OS X Yosemite 10.10.5 and trying to upgrade to OS X El Capitan. I'm in the App Store on the OS X El Capitan page: https://itunes.apple.com/us/app/os-x-el-capitan/id1018109117?mt=12
However, the download button is grayed out and there's really no way for me to upgrade. See image below:
How to solve this predicament?