Seems to be, yes. storing phosphates to help produce more ATP.
I'm missing the understanding on how ATP gets made, I guess it's adenosine diphosphate until muscle activation and then receives a phosphate from the creatine?
Yes, that is pretty much what happens. The creatine can donate its phosphate to any nucleotide, so any ADP that is in need will accept one and can then donate it in whichever energy pathway needs it.