Since you're employed by the parent company of the licensed store and not by starbucks, I don't think you'll be able to unionize with SBWorkersUnited. It won't hurt to reach out to them, though; they may be able to give you some guidance or at least point you to another union you could organize with.
If your licensed store is in a grocery store,
$1 will probably be the union you could organize with. That's especially the case if you're in a Kroger or Albertson's store since UFCW has many established unions at those companies.
Also, be aware that you will likely need to unionize your entire workplace, not just the licensed store.