Yes. If the Feds want to, they can enforce the federal law and fuck anyone and everyone over who violates federal law. State law doesn’t mean shit if there is a stronger federal law in the way. All it takes is one federal agent to buy pot from a dispensary and your “legal” operation now faces federal drug charges.
A64 allows adults 21 and older to purchase up to one ounce of marijuana from specialty marijuana dispensaries and grow up to six marijuana plants in their homes. Possession is limited to up to an ounce for personal use, but selling marijuana without a license, purchasing marijuana from a party who is not licensed as well as public use of marijuana will remain illegal.