No you subscribe as the moderator whom authenticated/granted the scope.
So,
if I authenticate myself to my client ID
And I want to listen to shoutouts (either direction) to my channel
Then broadcaster_user_id and moderator_user_id will be the same value.
If I want to listen to shoutouts for cohhcarnage
I don’t have get cohhcarnage to grant my clientID access as I am a mod on cohh’s channel
So I will use broadcaster_user_id as 26610234 moderator_user_id as 15185913
and I’ll recieve shoutouts made by any moderator on/to 26610234
TLDR:
moderator_user_id describes the user that authentcated to your Client ID to grant the scope
This follows that you only need the channel bot’s token as the channel bot will be a moderator.
You do not need to get every mod to authenticate. Just the broadcaster and one mod (which is most cases is likely to be the channel bot, or the broadcaster themself)
Or if using the Websocket transport then moderator_user_id will be whichever moderator has logged into that tool