What to use for http authentication

There is a line in the code above that says, "Credentials added with this method are only valid for use with SMTP. This method does not work for HTTP or FTP protocols.".

What is the correct method of passing credentials for a HTTP protocol in instance? A link to what to use instead, or some reasoning behind why it doesn't work would be extremely helpful.

---
#### Document Details

⚠ *Do not edit this section. It is required for docs.microsoft.com ➟ GitHub issue linking.*

* ID: 3184666e-cfe0-bc81-60f6-1ea2a68ce20e
* Version Independent ID: afae16a1-ac99-017e-2fb0-fcbcb8f77ab3
* Content: [CredentialCache.Add Method (System.Net)](https://docs.microsoft.com/en-us/dotnet/api/system.net.credentialcache.add?view=netcore-2.1#System_Net_CredentialCache_Add_System_String_System_Int32_System_String_System_Net_NetworkCredential_)
* Content Source: [xml/System.Net/CredentialCache.xml](https://github.com/dotnet/dotnet-api-docs/blob/master/xml/System.Net/CredentialCache.xml)
* Product: **dotnet-api**
* GitHub Login: @karelz
* Microsoft Alias: **ncldev**