To connect to the Smart TV you have to follow the next steps:
Connect to the Libere WiFi network. Select the network that corresponds to your building, typically containing the word "Líbere" and type down the password Staylibere.
Turn on the TV, press the "source" button and access the HDMI 3 source. If it doesn't work, try HDMI 1.
You will get a QR code that you have to scan. You can scan it with the camera on your phone or with a QR-reading application.
Go to your phone and open the app of your choice (Netflix, YouTube, Spotify, etc.).
Find the Chromecast icon and click on it.
There's a screen at the bottom with your room number. Click on it.
Search for the movie, song, or video on the streaming app you chose previously and enjoy!