Fully exit out of the game and Origin. - If exiting Origin isn't working, open Task manager (Ctrl-Shift-Esc) search for a file called ts4.exe. Click on it and select end process.
Restart the computer and try again to see if Origin automatically starts downloading any free and/or owned content.
If that doesn't work, try resetting the installation folder for Sims 4.
To do this, go to Origin and click Application Settings, select the Installs and Saves tab and re-select the location to install the game to.
For example: Install Sims 4 to: C:\Program Files (x86)\Origin Game