February 2020
@Chanip91 It's possible the item you're trying to install is corrupt in some way. Again in a clean folder, please try installing some other item. Start with something from the Sims 3 Store, if you own any content. (Riverview is free if you've registered your game.) If that works, you can try custom content. If it doesn't work, try another browser, specifically Firefox or Internet Explorer.
February 2020
I only have Sims 3 stuff from the store, bought with simpoints. I cleard out my folder and tried to install my stuff again, same problem.. I uninstalled origin and reinstalled it without any help. I have tried downloading from explorer and that doesn't work either.. black square in a few seconds, then nothing. I can play as usual, but not install anything. I thougt about unistalling the whole game and reinstall everything, but I'm afraid I don't get anything installed again..
February 2020
@Chanip91 There's a difference between clearing out the folder and moving it: sometimes the folder itself can be corrupted. If that doesn't help, please install Firefox and use it to download a store item. Sometimes a browser setting or a third-party plugin can block the download or cause it to corrupt as well.
If none of this helps, please create a new user admin account on your computer and try to install a store item in that account. (You won't need to reinstall Sims 3.) Use only letters and numbers, no special characters, in the account name.
February 2020
I moved it to my desktop as you described and started the game to get new folders. Tried to install a package, but still the same. Now I'm downloading origin and Sims 3 to another computer, just to check if it works. So tired of this problem...