<?php
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "https://dsg-api.com/clients/{client_name}/handball/get_matches_day?day={day}&client={client_name}&authkey={client_authkey}");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_USERPWD, "{User}:{Password}");
$content = curl_exec($ch);
curl_close($ch);
?>

curl GET -u "User:Password" "https://dsg-api.com/clients/{client_name}/handball/get_matches_day?day={day}&client={client_name}&authkey={client_authkey}"

Imports System
Imports System.Net	
Imports System.IO
Imports System.Text

Public Module Module1
	Public Sub Main()
		Dim url As String = "https://dsg-api.com/clients/{client_name}/handball/get_matches_day?day={day}&client={client_name}&authkey={client_authkey}"
		Dim myReq As WebRequest = WebRequest.Create(url)
		myReq.Credentials = new System.Net.NetworkCredential("{User}", "{Password}")
		Dim wr As WebResponse = myReq.GetResponse()
		Dim receiveStream As Stream = wr.GetResponseStream()
		Dim reader As StreamReader = New StreamReader(receiveStream, Encoding.UTF8)
		Dim content As String = reader.ReadToEnd()
	End Sub
End Module

response = requests.get("https://dsg-api.com/clients/{client_name}/handball/get_matches_day?day={day}&client={client_name}&authkey={client_authkey}", auth=("User", "Password"))