Sims 3 Launcher won't download or uninstall content

@shine64dg  I split your comment into its own thread, since the previous thread was quite old.

Try clearing your browser cache, or using a different browser.  Neither Safari nor Chrome works particularly well with the store, including the exchange.  One helpful step is opening the launcher before you press Download; sometimes that's necessary to make the download start properly.

It may also help to clear out your Downloads folder, inside your TS3 game folder in Documents.  The launcher sometimes has trouble reading the contents of an overfull folder.  You can store your downloaded files elsewhere, in case you ever need to reinstall, but there's no reason they need to stay in your game folder after the packs have already been installed.

If these steps don't help, try downloading into a clean game folder.  Pull your existing one out of Documents and onto your desktop, and launch the game to generate a new one.  Then try downloading just one item.  If it works, you can download the rest of the content you want, a few files at a time, and then move everything in Downloads from your new game folder into your old one.  Trash the new folder, put the old one back in Documents\Electronic Arts, and you should be able to install the content via the launcher.

If none of these steps help, please let me know exactly where the process is going wrong, as well as any error messages you see.