Fifa 20 demo, do you own this game or app?

I just launched the game and it works for me. Did you download the fifa demo in your account? Or do you have other family members who share the console? I know when you download a free trial if you have more than one account on a console each person
has to go to the miccrosoft store, find the game and click on install. Not sure if demos work the same way. If you are the only account on your console then it shouldn't be giving you an error message. It is a free demo you can't buy it. Hopefully a hard
reset straightens out everything for you.

I recommend contacting Xbox payment and purchases and requesting a call back from them. They can look at your billing history and make sure
you still own the digital license for the game. Thats what I had to do when Red Dead did the same thing to me. Hope this helps you out.

Keep Calm & Game On!

Try a hard reset by holding down the power button for 10 seconds until the console shuts off.

Unplug the power cable and wait for 5 min before plugging in back in.

That might fix the problem

Hello NiNjA,

We thank you for bringing this inquiry to our forums community, and understand that this involves an inability to launch and play a FIFA 20 demo on your Xbox One console.

We recommend trying a power cycle
of the console, but if the problem persists, try doing a
soft factory reset of the console, reset and keep games and apps to help reset
the operating system. Please note before doing this troubleshooting step, make sure to know your email and passwords for your Xbox profiles.

Try this out first and let us know the results.

Has Son 1 purchased FIFA17 or is this an EA Access Trial version?