Since you are saying you are noob to all-grain...
If you are doing BIAB then you could crush it to powder almost.
However if you not doing BIAB, then it might be good to start off with grain that isn't crushed as well as some of the more experienced brewer's will do.
You might well have a lower efficiency, but this appears to be a kit you got, and they probably figured the recipe for lower efficiency than what we'd want after the experience of a hand full of all grain brews behind us.
So I wouldn't dwell on it too much. Unless you are going to get a mill or have access to one. Just use it and see if your SG's match. If you have it milled more to where someone with experience might, then you might be fighting stuck mashes that take forever to drain.
If the recipe only gives you OG and FG, then put it in a Beer Recipe builder and see what the pre-boil SG should be. But make sure you adjust the efficiency of the recipe buidler to match the OG and FG stated as close as possible.