[TheLazySloth]

public OnPlayerSpawn(playerid)
{
new CheckForDarren[MAX_PLAYER_NAME];
GetPlayerName(playerid,CheckForDarren,sizeof(Check ForDarren));
if(skink==270) && CheckForDarren == "Darren_Kok" {
new string[128];
format(string,sizeof(string),"Welcome back Darren")
SetPlayerTeam(playerid, 1);
GangRank[playerid] = 1337;
SendClientMessage(COLOR_PURPLE,string);
}
return 1;

should be...

public OnPlayerSpawn(playerid)
{
new CheckForDarren[MAX_PLAYER_NAME];
GetPlayerName(playerid,CheckForDarren,sizeof(Check ForDarren));
if(skink==270 && strcmp(CheckForDarren, "Darren_Kok", true) {
new string[128];
format(string,sizeof(string),"Welcome back Darren")
SetPlayerTeam(playerid, 1);
GangRank[playerid] = 1337;
SendClientMessage(COLOR_PURPLE,string);
}
return 1;
}