I did it, and worked!!!
Some notes that may be important
- I turned the console on, with the latest update
- with my PC, choose to download by clicking on this guy link, selecting the Xbox One version as been told
- waited for the full download to start the game (game can be started by 70%ish early)
- started, entered my profile, choose to upgrade
- got a message "it's yours"
- close the game and then restarted the console
- (maybe you can skip this part to the next) opened the game again, still was the Xbox One version, choose to upgrade again and got a message "you already own"
- go into the store, choose the game, turned on the SX version, downloaded to full (can start like 90% of the download)
- restarted the console, turned on, started the game. There you go