Backwards compatibility no 360 account

The one thing that was not answered for you and this is assuming that the game is a 360 backwards compatible game and you are trying to do this on a xbox one is this.

The ONLY way to use MS account currency to purchase anything backwards compatible would be to do it directly on a xbox 360 itself you can not use MS account currency to purchase backwards compatible items on a xbox one or on the MS store online.

If it's backwards compatible it would only be available on the Xbox One as a backwards compatible game. Not on the 360

There are backwards compatible games available for the 360. Black is one of them.

The One store/website have never been updated to work with the currency system for backwards compatible content. The only way to purchase backwards compatible games with the funds on your account is through a 360 console.

Oblivion is backwards compatible so it will work on the One X. You can view a list of backwards compatible games at https://www.xbox.com/xbox-one/backward-compatibility/available-games

The game is backwards compatible with the 360, but not the One. In order for backwards compatibility to work, the 360 requires an official MS brand 360 hard drive.

That game in particular is not backwards compatible, so it wouldn't work. You can view what games are backwards compatible on the 360 here and compatible games with the One here