Downloaded scenario mod not showing in custom scenario menu

When subscribing to custom scenario mods they don’t show up as an option when selecting custom scenario in standard game options. I’m not sure if this is how you’re supposed to play them or not. I’m trying to play Age of Empires II DE: Three Kingdoms Cao Cao by PhillySouljah. Any help would be appreciated.

Don’t confuse scenarios with campaigns.
To play campaigns:
Main menu -> Campaigns -> Custom Campaigns -> Select appropriate campaign