I've been downloading 'fully furnished' lots with custom content, but when I load them in the game the only things that show up are walls and basic EA content. Many of the places I've downloaded from say the content is included and don't offer links to download any content separately. Am I doing something wrong? I downloaded a bunch of houses just because I wanted all the furniture that came with but I haven't gotten anything in my game! I just don't want to have to search for everything individually.

That's odd; the only time content wouldn't get into the game is if he content was from or was based from an EP you don't have. It's possible the CC was based off of meshes from one of the EPs you don't have, in which case it wouldn't show up or would be replaced by other content you have in-game

sims3pack files are notorious for doing as they like on a random bases, at least for me as a builder. I only install stuff I want to use, if it doesn't turn up I get really! annoyed. Package files are much easier like that, if it doesn't turn up it's a rubbish creator or I have forgotten to install it. sims3pack files just don't turn up for no apparent reason whatsoever, and then they often do install with the content despite the fact that I never even touched it while making the house. For sims3pack files I have to keep everything extremely tidy, because finding it back is close to impossible and if it won't install I don't want to use that creator again basically.

If you don't have the content needed package files shine in your inventory like a shiny nobody and produce nothing. Very easy to see.

I wouldn't ever download houses from someone on Youtube that doesn't list what they use and can't tell you what it is when you contact them. I don't have time for such rubbish.

... and if I sound aggressive now, it's because I've working on files or conversion all day, and I have a kitchen that glitch because it can't handle converting to package files. The last thing isn't a problem because the downloader will install the kitchen as intended, but some creators manage to make kitchens that doesn't glitch for a good word, and I wish I knew this on beforehand because then I would choose another creators kitchen.

If you download as it seems lots of lots and nothing follows, that requires more investigation into what you do and perhaps there is something wrong with your game.

If those lots were sims3packs, maybe check with Custard, if the content was really included with them?

Also, using Multipack Installer, you could convert your sims3pack into packages files. If more than one package gets extracted with this program (they'll be named with a string of letters and numbers), they were actually included in the sims3pack. You could drop them in your Mods/Packages folder (I'd suggest renaming the files to stay organised then), or you could try re-installing your lots through the launcher.

As said above, if the objects are not from another EP or from the Store, they should show up. And even then, if you don't have the EP, most items (e.g. chairs, lamps, etc.) should be replaced by an other object of the same type.

Thanks for all the help! I'll try using the multipack installer.