Have you received an email stating when your funds will be available? Once accepted, you will receive an email with further instructions on accessing the funds. See the TurboTax FAQ here for more information on your refund advance.
Please make sure the primary taxpayer information matches exactly the same as your Credit Karma account. Changing any information in one account like your password, phone number, mailing address or email doesn't automatically change it in the other account.
You have to apply for the refund advance before submitting your tax return. You can't apply for the Refund Advance after you file your taxes. For information on the Refund Advance, please see the information available here.