The difference and usage of 刚才 and 刚刚
刚刚 is an adverb.
刚才 is a noun.




我刚刚起床 means: I just got up.

我刚才起床 is kind of nonsensical as it is as it means something like:  I a moment ago got up.



刚刚 is going to be the more likely choice when you're expressing things you did just now a moment ago.