CreateUnifiedTeamSite_CSOM.cs

class Program
{
    static void Main(string[] args)
    {
        Task.Run(() => MainAsync());
        Console.ReadLine();
    }
}


static async Task MainAsync()
{

	string userName = "user@tenantName.onmicrosoft.com";
	string password = "password";

	List<KeyValuePair<string, string>> vals = new List<KeyValuePair<string, string>>();

	string tenantName = "tenantName.OnMicrosoft.com";
	string authString = "https://login.microsoftonline.com/" + tenantName;
	string resource = "https://graph.microsoft.com";

	AuthenticationContext authenticationContext = new AuthenticationContext(authString, false);

	string clientId = "<client-id>";
	string key = "<client-secret>";

	vals.Add(new KeyValuePair<string, string>("client_id", clientId));
	vals.Add(new KeyValuePair<string, string>("resource", resource));
	vals.Add(new KeyValuePair<string, string>("username", userName));
	vals.Add(new KeyValuePair<string, string>("password", password));
	vals.Add(new KeyValuePair<string, string>("grant_type", "password"));
	vals.Add(new KeyValuePair<string, string>("client_secret", key));
				
	string url = string.Format("https://login.windows.net/{0}/oauth2/token", tenantName);

	using (HttpClient httpClient = new HttpClient())
	{
		httpClient.DefaultRequestHeaders.Add("Cache-Control", "no-cache");
		HttpContent content = new FormUrlEncodedContent(vals);
		HttpResponseMessage hrm = httpClient.PostAsync(url, content).Result;

		AuthenticationResponse authenticationResponse = null;
		if (hrm.IsSuccessStatusCode)
		{
			Stream data = await hrm.Content.ReadAsStreamAsync();
			DataContractJsonSerializer serializer = new
			DataContractJsonSerializer(typeof(AuthenticationResponse));
			authenticationResponse = (AuthenticationResponse)serializer.ReadObject(data);

			var accessToken = authenticationResponse.access_token;

			Stream groupLogoStream = new FileStream("C:\\groupassets\\logo-original.png", 
                                            FileMode.Open, FileAccess.Read);
											
			var group = UnifiedGroupsUtility.CreateUnifiedGroup("displayName", "description", 
                            "MyModernTeamSite", accessToken, groupLogo: groupLogoStream);

			
			string groupUrl = group.SiteUrl;
			string groupId = group.GroupId;
        
		        // Get all groups in the tenant
		        //List<UnifiedGroupEntity> groups = UnifiedGroupsUtility.ListUnifiedGroups(accessToken);

		        // Update description and group logo programatically
		        //groupLogoStream = new FileStream("C:\\groupassets\\logo-new.png", FileMode.Open, FileAccess.Read);
		        //UnifiedGroupsUtility.UpdateUnifiedGroup(groupId, accessToken, description: "Updated description", groupLogo: groupLogoStream);

		        // Delete group programatically
		        //UnifiedGroupsUtility.DeleteUnifiedGroup(groupId, accessToken);
								
		}
	}

}