ASP.NET Core 2.2 send emails using Office 365

Question

I'm trying to send email from my ASP.NET core 2.2 web application, using my company Office 365 email account (we have Office 365 Business Basic package).

I found this code on StackOverflow:

MailMessage msg = new MailMessage();
msg.To.Add(new MailAddress("someone@somedomain.com", "SomeOne"));
msg.From = new MailAddress("you@yourdomain.com", "You");
msg.Subject = "This is a Test Mail";
msg.Body = "This is a test message using Exchange OnLine";
msg.IsBodyHtml = true;

SmtpClient client = new SmtpClient();
client.UseDefaultCredentials = false;
client.Credentials = new System.Net.NetworkCredential("your user name", "your password");
client.Port = 587; // You can use Port 25 if 587 is blocked (mine is!)
client.Host = "smtp.office365.com";
client.DeliveryMethod = SmtpDeliveryMethod.Network;
client.EnableSsl = true;
try
{
    client.Send(msg);
    lblText.Text = "Message Sent Succesfully";
}
catch (Exception ex)
{
    lblText.Text = ex.ToString();
}

However I got this error:

    The SMTP server requires a secure connection or the client was not authenticated. 
    The server response was: 5.7.57 Client not authenticated to send mail. 
    Error: 535 5.7.139 Authentication unsuccessful, SmtpClientAuthentication is disabled for the Tenant. 
    Visit https://aka.ms/smtp_auth_disabled for more information. [HK2PR03CA0048.apcprd03.prod.outlook.com]

And on the link on the error above they stated: I followed the link and enabled the Authenticated SMTP, like the pic below: However, then I got this error:

The SMTP server requires a secure connection or the client was not authenticated. 
The server response was: 5.7.57 Client not authenticated to send mail. [HK2PR02CA0162.apcprd02.prod.outlook.com]

Then i searched for that error but couldn't find any information.

Now I have no clues to continue, please help me to fix this, thank you so much.