Aurion credentials vs security user

Following the online doco https://unifysolutions.jira.com/wiki/display/IDBAUR50/Aurion+Agent for Aurion and it is a little light when it comes to the Aurion Agent and user credentials.

We have required fields Security User and password, where security user is described as The name of the Security User account used to connect to the Aurion system.

Then we have credentials:

The type of credentials used to connect to the target system.

any idea what that means? If I select custom I get the option for Account name and password - the other options are none, default, defaultcredentials and defaultnetworkcredentials, but nothing in the doc that I can see that tells me what any of those mean.

Is there a doc somewhere that tells us more about Aurion?