I have a Chromecast linked to older Panasonic TV via a HDMI cable. I got caught out by the fact the Chromecast attachment needs to be powered (embarrassed by my eldest son there). You will also have to have the Chromecast cast app on the device you are casting from. We also had to name the TV to which we are casting.

I have cast from my mobile phone and from my Android tablet and this is what i do.

Step1
Get the TV setup to take the stream from the correct HDMI port. 

Step 2 
Start Paramount+ on your phone or tablet

Step 3
Select the game you want to watch on your device

Step 4
There should be a small rectangle in the top right corner which will be grayed out. Hit that rectangle to cast. If there are other devices like Google nests, then you select the TV you are casting to.

Hope that helps