I just bought a used TCL Roku TV from a friend that seems to work great but when i try to connect my Vizio sound bar I already had it doesn't work. I was using the sound bar on a Phillips flat screen so I know it works and the previous owner was using a sound bar, don't know what brand, on the TCL and it worked for them. The difference is they were using the HDMI output but my sound bar doesnt have HDMI connection, only has the sub output and left and right input, the yellow white and red cables. On back of the TV there are Red, White and Yellow connections. I don't have the manual for my sound bar and the man I got the TV from no longer has the manual for it. I've gone into settings and turned off the TV speakers but then I had no sound at all. Basically I'm up that certain creek without a paddle. Before I go out and mad and buy a complete home theater system I thought I would see if anyone here has any ideas.
From your description you will probably need to convert the optical audio output that the TCL probably has to analog for the soundbar. The optical output usually has to be turned on in the TV menu.
I would suggest you google for the owners manuals for the TV and soundbar since you know the model numbers and we don't.