Basic solutions:

------------------------------------Section 1: Troubleshooting the Installation----------------------------------------

1.1 Verifying DLC Purchase:

Checking your purchase history and ensuring that the Criminal Enterprise DLC is associated with your account.
If not found, contact Steam Support for assistance in retrieving the missing DLC or rectifying any purchase errors.
1.2 Checking Game Files:

Verifying the integrity of the game files via Steam's built-in function.
This process will identify and fix any corrupted or missing files that may be causing issues with the DLC installation.

1.3 Updating the Game:

Ensuring that you have the latest version of the game installed.
Updating your game can often resolve compatibility issues and enable the proper integration of DLC content.

-----------------------------------Section 2: DLC Activation and Redemption----------------------------------------

2.1 Steam Library Activation:

Accessing your Steam library and locating the Grand Theft Auto V game.
Right-clicking on the game and selecting "Properties."
Navigating to the "DLC" tab and ensuring that the Criminal Enterprise DLC is checked for installation.

2.2 Redeeming DLC Key:

Checking your purchase confirmation email or receipt for a DLC key.
Opening the Steam client and selecting "Games" from the top menu.
Choosing "Activate a Product on Steam" and following the on-screen instructions to redeem your DLC key.

------------------------------------Section 3: Contacting Rockstar Support-------------------------------------------

3.1 Submitting a Support Ticket:

If all previous steps have been followed without success, it may be necessary to contact Rockstar Support for further assistance.
Providing them with detailed information about your purchase, installation attempts, and any error messages encountered will help expedite the resolution process.

3.2 Patiently Awaiting a Response:

After submitting a support ticket, allow Rockstar Support some time to investigate and respond to your issue.
Typically, they will provide guidance or a resolution to help you acquire the Criminal Enterprise DLC.