Hello everyone. I was having issues installing sims3packs through the launcher. It would just show a black screen for more than ten minutes and never install anything. This is what I did to fix it.
Open Documents\Electronic Arts/The Sims 3/Downloads select the packs you want to install and either drag and drop into the Electronic arts folder are copy and paste
Rename The Sims 3 folder I renamed to The Sims 3 old
Open the launcher
There should now be a new The Sims 3 folder open it and navigate to the downloads folder drag and drop the packs or paste them
They should now appear in the launcher downloads tab
Install as normal
Exit the launcher (make sure it is fully closed)
Navigate back to your Electronic arts folder Cut or drag and drop the folders from your The Sims 3 old or whatever you named the backup to the new Sim 3 folder
I recommend deleting the Cache files and the dcbackup all put the ccmerged
I hope this helps.