From what I understand (reading on the Apple support forums) - an app needs twice it's size to download and install. Once it's installed, the extra space is freed up.
So, the FIFA app [doubled] will require more space than you have free on the iPad. My suggestion is to delete another app or two to get the space you need, download the app you want, then you can [probably] put the other apps back on.
Hope this clarifies.
Marilyn