Android TV is NOT Android OS for phones. You are very limited on Live TV sources.
try updating your tv through local usb update worked for me find your model here https://tclnordic.zendesk.com/hc/en-us/articles/360012806599-TCL-TV-software-downloads
then follow the steps
usb bigger than 4gb formatted fat or fat32
downloads update for your model of tv
unpack/unzip the zip file
enter the file you just unzipped will see another zip file inside do not unzip that but copy or drag that zip file to usb
plug usb into tv
go to settings
go to about
go to software update
click local update
it should find the update and install automatically
Live TV app doesnt work without a source added, either add a playlist via another app that is integrated with LiveTV or a network tuner as a source like HDHomerun