I also found out i forgot to add 3 lines in the MT4 code, so it looks like this now.
string url = "https://johnnylai.me/license/customers.php";
string headers;
char post[];
int accountNumber = (int)AccountInfoInteger(ACCOUNT_LOGIN);
string postText = "account_no="+IntegerToString(accountNumber);
StringToCharArray(postText, post, 0, WHOLE_ARRAY, CP_UTF8);
char result[];
string resultHeaders;
int response = WebRequest("POST", url, headers, 1000, post, result, resultHeaders);
Print(__FUNCTION__," > Server response is ", response, " and the error is ", GetLastError());
Print(__FUNCTION__," > ", CharArrayToString(result));
return(INIT_SUCCEEDED);