I read that once your tax refund was approved and you chose to have your tax refund to be deposited in that credit karma account I read that it only takes 15 minutes

The option that you are describing is for the Refund Advance option. Choosing to have your fees alone being direct deposit into the Credit Karma account doesn't mean you will get it in 15 minutes. 

 

Did you apply for The Refund Advance Loan Option? 

 

Click the link below for more information

 

Offer details and disclosures for the Refund Advance program