You’re going to have to use some kind of a live player counter to find the players on each team. (provided below):
Then, use a lifecycle wired to a team switcher Player Knocked Out → Switch Team to Spectator. After that, wire that same lifecycle to the counter, decrementing it.
(when 2 people reply with the same thing and the same guide)
You should probably use LL22’s version, it’s easier to do.