Coocoo girl - did you ever manage to solve this?
I formatted my C-drive and naturally had to do a complete reinstall on Sims, too, and after downloading all my Store content again, I noticed Riverview is the only thing that won't install! I get a notification about needing an update. I found posts about people getting this error with a fully patched, up-to-date game at the official forum, and the suggested fix was to download and install it trough the in-game store. I did this but it won't install.
I have deleted and redownloaded the file 3 times, it's always the same size and always gives the same error, so I don't think it is a downloading error / error with the file.
Any suggestions? :/
By the way, as I re-installed everything, I noticed I had been missing a lot of my purchased and installed store content from my game, without noticing! So there really seems to be some issues with the content, as Ricalynn explained.