After the Shark Cash Card purchase, a Rockstar Code will be emailed to you or printed on your receipt by the retailer. Then, you can follow the steps below to redeem the code:

Via Rockstar Games Social Club

1. Visit the Rockstar Games Social Club and log in to your Grand Theft Auto V account.
2. On the Game Activation page, find the "Use Rockstar Code" button in the Grand Theft Auto V section and click it.
3. Enter your Rockstar Code and click "Activate."
4. Your Shark Cash Card will be credited to your account automatically.

Via Rockstar Game Launcher

To claim, please follow the instructions on How To Redeem Rockstar Activation Code.