Reinstall Forza Horizon 3?

I had to uninstall Forza Horizen 3 for reasons of disk space. Since I now have the necessary storage space, I wanted to reinstall the game and could no longer install it on app store. I have an xbox one s, could you tell me why this is or whether you can no longer install it.

Have you got FH3 for free with Xbox Gold and you don't have an active Gold membership right now?

When I got the xbox there was a code with it

Have a look in your library, there's the tab where all your games are listed, including those that have not been installed. FH3 should be there somewhere.