Looks like you already own this - Halo Wars 2 DLC Awakening the Nightmare

Hi and thanks for reaching Microsoft Xbox gamer's community. My name is Josef.
I'm an Independent Advisor and a Microsoft Xbox user like you.

Hope you're doing great today despite this
STELLARJEANS35

May I know if you tried all this together with the expert?
Open Settings, click Update and Security and then Windows Update;

Click Check for Updates;

Click the Download and Install Now option, if available (Install optional updates as well)

Also, check the Microsoft Store for any updates on the Xbox apps and its services and update everything too.

Now, sign out from your account on both Xbox app and Microsoft Store and do this:

Go to windows settings > apps > search for gaming services app > click on it and select advanced options.

After that, click repair and then reset

Then do the same for the Xbox app and Halo Wars:

Go to windows settings > apps > search for Xbox app > click on it and select advanced options.

After that, click repair and then reset

Finally do this:

Step 1: Open the Run window by pressing Windows + R key.

Step 2: Input WSReset.exe in the Run window and click OK.

Step 3: Then a command prompt window will appear. After a few seconds, Windows Store will open.

Sign in again on both Microsoft store and Xbox app with your account and try again

If yes, may I know if you have installed the game and the DLC in your C: drive?
If not, can you move both things to the C: dry and test again?

Hello!

I'm an independent advisor and a member of the Xbox Community.

I will be glad to help you.

The base game is Play Anywhere, that is, you can use the same license on console and PC, but this is not the case for the DLCs, as these are listed separately in the Microsoft Store for each platform.

DLC for console:

https://www.xbox.com/games/store/halo-wars-2-aw...

DLC for PC:

https://www.xbox.com/games/store/halo-wars-2-aw...

I hope the information has been clear, I will be attentive to any questions you may have.

Best Regards.

to add to the other responses;

there can be Full expansion(s) that will be not included in the season pass.

for example Halo wars 2 got an additional DLC that wasn't included in the season pass, named Awakening the Nightmare.

Always look in the what's included to see what you will get before purchasing.

Hi Piquet21 sorry to hear about your problem. If you go into "my games and apps" than press start over Halo Wars 2, the DLC should be there in the ready to install section.

Please note that the Awakening the Nightmare DLC is not covered by the season pass.

So wtf indeed, especially with this information :

"

With the release of the new expansion and several months of updates to Halo Wars 2 since launch, the Ultimate Edition of the game will be replaced with Halo Wars 2: Complete Edition. The Complete Edition includes the base game, all Season Pass content and
the Halo Wars 2: Awakening the Nightmare expansion, making this a great package for anyone who is looking to jump into the Halo Wars 2 experience.

"