#define CLANTAG "[DZ]" // example
#define CLANPASSWORD "testpasscode" //Enter the clan password

It should be something like this


public OnPlayerConnect(playerid)
{
        new string[500];
        new nome[24];
        GetPlayerName(playerid, nome, 24);
        if(strfind(nome, CLANTAG, true) == 0)
        {
                format(string, sizeof(string), "{FFFFFF}Welcome%s!\nYou must confirm the clan password %s.\nEnter the clan password and confirm.", nome);
                ShowPlayerDialog(playerid, DIALOGCLAN, DIALOG_STYLE_INPUT, "Clan", string, "Confirm", "Exit");
        }
        else
        {
                SendClientMessage(playerid, DZ, "Welcome!");
        }
        return 1;
}