Yes, if you're physically located in a jurisdiction where a product is offered, you'll be able to access any DraftKings website and/or app using your existing DraftKings login credentials.
DraftKings provides a seamless single account experience for customers, leveraging the same account and login details for Daily Fantasy, Sportsbook, Casino, and Marketplace. If it’s the first time you’re logging in, you may be asked to provide additional information to verify your identity.