PH help needed

[Tut69]

I just acquired a pallet of 100% pure grape juice concentrate. It expired two months ago. 1/2 gallon jug says no added sugars (and no preservatives). I dropped a hydrometer into a jug and it reads 1.064. I know that’s probably not very accurate in juice but it’s a reference point if nothing else. I’m thinking about fermenting it as is but am open to suggestions. I have EC1118 yeast. Two questions. What, and how much yeast nutrient do I need? Secondly, PH is showing 3.45. Should I rise PH and if so, with what method?
Thank you in advance.