How do I get the game pass that we have been using for years on xbox to show up on our new PC?

New PC build. My son has signed into his microsoft account and I can see his username in the xbox app. I can go to his profile info and see all the achievements for the games he plays on xbox. But when we go to game under the game pass section, it wants us to purchase them and acts like we do not have a subscription. I guess technically the subscription is under my account. On the xbox, this does not seem to matter and he is able to download using his account. I assumed that when he signed into his account on the PC, it would see that he is setup as my child under my family account and therefore see that he has a valid game pass subscription via me. What am I doing wrong?

Edit: Just had a thought. I am going to login to the PC using my account and then login to the xbox app using my account and see if that then does something to register the PC to my account and then maybe that will allow things to work under my son's account. I will report back but feel free to tell me this is wrong before I do.

:)