360 compatibility

With the Xbox One being able to play 360 games from November, I have a question.

All the references I’ve seen are about downloading them if you owned them in the past. What if you’ve not owned them, can you still purchase them via the backwards compatibility? What if bought a physical copy but no longer have the disk?

Or have I just completely misunderstood the whole thing?

If you bought it digitally, you can redownload it digitally with no cost.

If you bought it physically you need the disc to install it on the Xbox one and play it like any other disc based Xbox one game. No disc, no play.

Basically, if you own a digital game on Xbox 360, it will show up on your Xbox One once that game is put into the program. You can still go online and buy digital games for the 360 and they will show up just like the ones you already have. And you do need to the disc to play physical games.

As others have said, if purchased digitally, it will show as “ready to download” in “my games and apps.”
If you have the physical CD, you’ll be able to use that, as well.