Get clients

public void OnPluginStart() {
    HookEvent("round_start", EnableAutoSpawn);
	...
}

public Action EnableAutoSpawn(Event event, const char[] name){
    for (int client = 1; client <= MaxClients; ++client) {
        if (IsValidClient && GetClientTeam(client) == 3) {
            ServerCommand("mp_respawn_on_death_ct 1");
            CreateTimer(1.0, DisableAS, client, TIMER_REPEAT);
        }
    }
}