How to set up cross-gen progress?

I bought the $85 deluxe version of the game for xbox, it came with both the current gen game and the next gen game.

I just "got lucky" and scored a new xbox series X from target for pickup in a couple hours.

I'm going to keep my xbox 1X for use in spare room, and set up my new box in my office.

I want to be able to play on either box and progress the same saves.

How do I set up cross generation saves/progress?

Thanks!

DD is saved on the server, so you don't need to do anything there. For RTTS and franchise I think you just need to upload your data to whatever cloud service Xbox offers. I could be wrong about that though

So do I need to link my xbox account in game from old system?
Somebody has to know how this works...

In case anyone cares to know... I created a MLB21 account, and linked my xbox account to it on this website. Then I went into my game on my xbox 1X, went to my profile and noticed it said "account linked" or something like that. I then logged out of xbox 1x and signed into xbox series x.
Everything worked, all my saves are on both systems now. I can play on either system and my progress shows up on the other.