There are a lot of libraries out there with the same name but have different functions within them. However, the good news is that the 1307 and the 3231 are (almost) the same internally - close enough to be able to use the 1307 library with the 3231. So I would suggest getting the library used in the instructions, you should be ok.
To be pedantic the 1307 has a Clock Halt flag which tells you if the clock is running or not. The 3231 doesn't have this flag.
But, on top of that, as PaulS said:
You are trying to call a method on an instance you have not created.