In simple terms: When you open SimCity BuildIt, your device sends a digital key to EA’s servers saying, "I am Mayor X, and here is my Game Center/Google Play/EA login." The server then verifies that key.

You’ve just opened SimCity BuildIt , ready to collect your taxes, start a new War league, or redesign your capital city. But instead of the familiar skyline loading screen, you are met with a chilling pop-up window:

But don't tear down your city in despair. The "11007 error verified" is a known, fixable authentication handshake issue between your device and EA/Track Twenty’s servers.