Microsoft Store game-can't play same game on 2 different accounts-Why?

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 Jynxir

Please try and double check the next:

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 the Xbox app, Microsoft Store and Vegas downtown slots app and do this:

Go to windows settings > apps > search for Vegas downtown slots 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 Microsoft store Xbox app and Vegas downtown slots app with your account and check if finally the issue has been solved

The fact that I own 2 copies of a game on 2 different platforms and can't play them together on the same network without making throwaway Microsoft accounts seems pretty ridiculous. If I have 3 copies of the game I then need 2 other Microsoft accounts to keep up with. There has to be a better way.

If you bought the game in the past on the Xbox 360, make sure you sign in with the same Microsoft Account email that you used back then to buy the game digitally.

If you use a different Microsoft Account email, the store can't know that you are the same person with a different email, or if you are a completely different person with a different email.

Since every digital purchase is tied to your Microsoft Account, you need to sign in with the account that originally bought it on the Xbox 360.

If you still have the disc, simply insert the disc to play it.

Of course the 2 systems are not going to play together in anyway. Why would they. While the game might be the same BF4, COD, Madden etc the games are very different. Different servers, different hardware, different OS's. Nothing is the same between them.
Same with the PS4 and PS3. You can't game between them.

Same issue, when I click on "play on your PC" on the microsoft store, a white window of microsoft store appears and I can't do anything... Do you have the same problem ?

Slightly different I can't even download the game, it says it is starting to download and then just stops after a minute or so.