If you need simple user+password authentication to the URL, then the dialog does support inputting the username and password fields:
The value in these fields is passed in the header of the https request on header field names that are commonly required by many web servers.
Some web servers require getting the credentials on different field names in the header. For this, you can use the API's custom-header field with the sub fields of header-name and header-value.
Essentially, you need to know how your web server / provider that hosts the network feed text file wants to get the authentication credentials.