probably a dumb question, in the past ive downloaded lots with cc that just came along with it, i was browsing and saw a creator write certains things were required to download first and others were included...whats the difference? im uploading a house including bespoke build items for example...will the items not be included? is there an extra step i need to take? sorry for the dumb question

I'd have to see the upload to be sure, but I'll guess here. What kinds of things were required to download?

If they are hacks like CEP or HugeLunatic's Rugs Off-Grid, it's just common courtesy to not include hacks with downloadable lots if they are already available for download somewhere else. Creators may use certain hacks while building their lots, and if you don't have those same hacks then the lot may not look and function the same when you download it into your game. If, lets say, a custom recoloured poster is included in the lot, and the creator says you need CEP, if you want the custom poster recolour to show up properly ingame you need to install CEP as well as the poster.

If they are CC objects (chairs, tables etc) some CC creators do not allow them to be included with lots, so they need to link to the download separately.

Sorry if I misunderstood your question, I hope I was of some help.

When you are uploading to Mod The Sims something with custom content- you need to provide functional links to where the custom content required for your upload to be playable to downloaders can be obtained.

Here you can find guidelines for a lot. Link