Fallout 1st

The link Jesse gave you is for the XBox version, this one is for XBox Game Pass on PC:

Fallout 1st (Windows) — Fallout 1st (Windows) – One-Month Membership | Xbox

Note the (Windows), that's the difference.

I tried restarting my PC, the game (obviously). Checked to make sure I have the right one, unless the game didn't send me to the right one, but it says windows. Tried launching it from the Microsoft store app and the Xbox app. (Also checked billings and it says completed.)

Hello, since it's already showing as owned in your wife's console, i would recommend following the steps mentioned on this link to resolve the issue : Troubleshoot game or app installation problems on Xbox One | Xbox Support.

You will need to talk to Xbox support. We in the forums do not have access to the system to assist with these type of issues unfortunately.

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 Stephanie

Do you play the game on Xbox or PC?
Also, did you purchased the subscription inside the game or did you do it via Xbox.com?

In the meantime, are you able to see this subscription active in your account ( https://account.microsoft.com/services ) and with status completed in your order history? (https://account.microsoft.com/billing/orders)