Error 0x803f9006: Unable to Launch Game Pass Titles on Xbox Series X

Ok I have both versions of GTA downloaded on my series x the Xbox one version works fine on the series x I then downloaded the series s/x version on the series x I then launched the game and it gives the error message

Are you playing on the account that purchased the game?

Error 0x803F9006 occurs when you start a game or app on your Xbox console | Xbox Support

And, if it were not backwards compatible, you might have to wait until the release of Xbox Series X, as they have said they have stopped working on bringing Backwards Compatible titles to Xbox One until the Series X launch to get Backwards Compatibility
up and running on the Series X. Form there, I imagine they will move back to bringing titles to both Series X and Xbox One for a few more years.

They won't become obsolete, the Xbox 360 was still supported for years after the Xbox One launched in terms of both third party games, and dashboard updates. I wouldn't expect too much in the way of brand new titles, but the consoles will still work and
I'd imagine they'll continue adding Xbox One titles to Game Pass for years to come. The plan seems to be that all Xbox One titles will work on the Xbox Series X, so I would be shocked if we don't keep seeing things added to Game Pass.

Same here (Germany, Xbox Series X, Game Pass Ultimate).

I have downloaded the Game Pass iOS app which allows me to select on which Xbox (One X or Series X) I want to install the game on but it fails with "Es ist ein Problem aufgetreten" (An Error occurred).