I entered the correct login but my iPhone 5c said that the login was invalid

As the title says, I tried to login to my iPhone 5c and I'm sure I've entered the information correctly, but the phone says that the login information is invalid. I know the login info is correct, I've carefully typed out the password and Apple ID multiple times. Does anybody know why I can't log in?

If it helps, I'm using a Gmail address as opposed to an iCloud email, because the phone wouldn't let me create an Apple ID either, so I had to create it on my PC.