Sims 4 won't download onto my windows 10 laptop !

Do you have any anti-virus or other security software? Try turning that off for the download.

This is what is advised:

Download doesn't start 

• Most often the Firewall or Antivirus Program blocking the connection. Make sure to add Origin.com as an exception and check the quarantine if it's not blocked.
• You can also try starting Origin as administrator.
• You have Proxies turned on --> Turn them off in your Internet settings.
• Last but not least, check that no other programs interfere with Origin. Best way to do so would be running a Clean Boot.
• Reset your hosts file 
  
  Source: http://answers.ea.com/t5/The-Sims-4/FAQ-Serial-Codes-Game-Activation-and-Download-Issues/td-p/4228232