My home xbox setting & download code from game

You certainly can. First you would need to set one console as Home. This should be the console that is used by others in the house the most. This is because the Home console can share gold and digital purchases to other gamertags on that console.

Click this link to learn more about Home and how to set it

https://support.xbox.com/games/game-setup/my-home-xbox

If the game that you purchase does not automatically download to the other console then you would just need to search your Ready to Install list and download it to that console.

First you can only have ONE xbox set as a profiles home xbox at a time.

When a code is entered into the system for your profile whichever console is set as your home console it will automatically download to that console.

I did redeem the code on my account, as there was no warning that doing so would make it "my" game (on the 360 anyone could play the downloaded games regardless of "ownership") and because their accounts had not yet been set up. As for making the Xbox my
home Xbox, I have my own Xbox that I also used my account to download Halo 5 (on the same afternoon) and I have that Xbox set as my home Xbox. And since only one console can be the "home" console, that won't work.

If the code was added to your account and not his, make sure you have the console set as your Home console. This will allow you to share gold and games with his account. Game Pass itself does not share, but games downloaded from the pass will. So you would
need to install the games from your account first and then he can play them. https://support.xbox.com/en-US/games/game-setup/my-home-xbox

My guess is that whoever owned it previously had set it as their home xbox, and didn't properly remove all their data before getting rid of it.

When you set a console as your home xbox, any games you purchase automatically download to it. So, even if the previous owner has a new console, anything he/she buys will download to your console.

You could try going into Settings, then My Xbox and then selecting My Home Xbox to see if setting it as yours stops their stuff from downloading but as far as I know, the only way to stop it is for them to set another as their home xbox.