A satire is only as sharp as its subject, and writer-director Quinn Shephard has plenty to play with in “Not Okay,” targeting the emptiness of social media and the facade of influencer culture. She does so through Danni Sanders (Zoey Deutch), whom we’re told up front in a tongue in cheek pre-credits warning is an “unlikable female protagonist.” That ensures we never feel too much sympathy for Danni, even as Shephard flirts with giving her a redemption arc of sorts. How much Shephard is willing to let her off the hook becomes its own little narrative within the narrative. Danni is a photo edito…