Ok, so I just bought the Forza Horizon 3 Ultimate edition and I’m having trouble downloading the two bonus DLC packs they give. Anyways I get to the Rockstar DLC car pack and its free (thats a start), I try to download, but then this “market place error” comes up.
Have you rebooted? Are there any updates to install in System in your console settings? You could try unplugging all your equipment - console, router, and any computer with the Xbox App linked to your console and reboot again.