I was excited to hear about backwards compatibility since I got rid of my 360 a while ago and they're still giving out 360 games for free, but I have a problem when trying to download free games from the Xbox marketplace website. I scrolled down the Plants Vs Zombies page (since that's what's free this month), and click where it says "already purchased; download to Xbox 360." When I do, it gives me the above error. I've looked all over other forums and communities to no avail. As far as I know I'm not part of a family pack (or whatever that is. I had no idea such a thing existed until today and still don't know what it really is). My mom has my parent account, which does not include an Xbox Live account or its own gold subscription (I'm the only one in the household with a Live account at all), and I point that out because I'm not sure if a parent account can purchase games with gold if the child account under them has a gold subscription (aka use their child's gold subscription).
I don't particularly care about PvZ, but I really want to figure this issue out soon so I can get as many 360 games on my Xbox One once the feature is released. It's also clear to me Microsoft didn't really think out how poorly free 360 games mesh together with the upcoming BC feature on Xbox One at present, as most Xbox One users probably haven't had a 360 for some time, making the purchasing and usage of these 360 games all but impossible for most gold members under 18 (like myself), and people with other bad circumstances. (perhaps that will be my draft for a new change .org petition! lol)
Also, and I know this doesn't a darn bit of difference, but I'm 16 (17 next month), and I kind of wish I could do this without my parents' help.