You can only login with the new version of the app, in order to enjoy an ad- free experience and HD quality videos.
Go to www.viki.com from a laptop, desktop or mobile device. Sign in to the account you want to login on your Smart TV.
After a successful login, open the Viki app on your Samsung Smart TV and click on the Green button (Letter B) on the remote control.
A code will popup, use that code by visiting https://www.viki.com/samsungtv on your laptop/desktop or mobile device.Type the code you see on your TV screen and click on 'Link'.
Once the account is linked, the app might restart.
To logout, simply press the B button (green). After login out, you'll need to follow the same steps to log back in. Enjoy!