Creating a group channel is not mandatory.
All you really need to do is add a side chain-able compressor (The Portico is superb) and activate the sidechain button. This tells the compressor to listen for it’s input from a different source to the one it is inserted on.
Now find the track you want to use as the trigger (or key signal) and in it’s sends, select the sidechain input you want to send it to. Set to 0dBFS for starters and tweak from there.