I always download CC, never had a serious problem until a couple of months ago when it corrupted my game and I lost all my saves, progress and all, so I went back to basic, and was able to retrieve it all.
now, it’s happened again, but this time the CC all still works, but since I downloaded the Legacy Edition (no choice, it wouldn’t let me play unless I did) I’ve lost my saves and can’t access my Library like I was able to last time. My friend though, went into her account and searched me and found all my lots and households so it’s definitely still there, but I just can’t access it now. It won’t even let me access other people’s lots and households to download i can’t find the option for it, it only shows the sims 4 base game downloads
"Do online features still work in The Sims 4 Legacy Edition?
The Gallery, game banners, and social integrations are disabled. The Sims 4 Legacy Edition will not display or allow any purchases of content released after the update happens."
Unfortunately, this means that you won't be able to download anything from the gallery.
Your save files are supposed to transfer automatically from the default game to the Legacy Edition, but if they're not showing up for you, check that your saves in your normal Sims 4 folder (usually Documents/Electronic Arts/The Sims 4/saves) are copied into the Sims 4 Legacy Edition folder (usually Documents/Electronic Arts/The Sims 4 Legacy Edition/saves). If they're not, simply copy and paste them over. As always, when moving saves around, I'd recommend you copy your saves folder to your desktop or a similar safe location to back them up.
There are more details on the features and limitations of The Sims 4 Legacy Edition in that FAQ, linked above.
Hope this helps.