I'm signing into my account for the first time in seven years just in case someone else googles 2k20 coach mode and happens to stumble across this thread and makes the same mistake I did. Simcast live is not at all what the OP is asking for. Simcast live is just dots moving around on the screen representing the players, you don't actually get to watch the game in real time. You do get to call plays and control substitutions in real time etc. But you do not get to watch the actual game play out CPU vs CPU with animations in broadcast view etc.
In years past people discovered workarounds so that you could actually watch the games play out. But the old work arounds don't seem to work in 2k20. In 2k16 you could go into simcast live before tip off, wait for your team or the opponent to score, then save and quit. When you'd re-enter you'd be able to call plays, do substitutions and actually watch the game play out CPU vs CPU rather than the dots. The only issue with this is that it did require comprehensive adjustments to the sliders for the game to play well.
This isn't available in 2k20. But what is extra insulting is that after every play you can check instant replay. So the game does actually play out, you just can't watch it.
I made the mistake of picking this game up and thinking they had finally implemented a viewable coach mode. I spent days setting up a myleague only to be thoroughly disappointed when I launched the game and couldn't actually watch and coach the game at the same time. You either get to watch it, but not control anything using pure cpu vs cpu. Or control everything, but only get to see dots floating around like it's 1996.
I'm just making this post so somebody doesn't read the quoted post like I did and make the same mistake.
Aside from this the game is fantastic though lol. So I don't regret picking it up.