@colejs - Non-authenticated respondents will continue with any survey flow outside the Authenticator. Example survey flow:

Authenticator
    Authenticated Block
Non-authenticated Block 

So they can’t fail the authenticator and continue in in the same flow? I want the failed still to take the same survey. Would I need to duplicate the survey flow for each condition? 

You could do something like this:

Authenticator
    Set Embedded Data: authenticated = 1
Rest of survey flow 

First off, thank you for your time. However, I am sorry. I don’t understand.

UNITID is in the url string. If the UNITID in the string matches the contact list that the authenticator is pulling from, then the respondent continues. If,  not they get the faile message, “Unable to log in with the information provided.” I don’t understand how the flow will bypass that failed message. 

In Authenticator options, set Maximum Authentication Attempts to 1. If the Authenticator fails, there will be an error message, then click the Next button to continue.

I would put the Authenticator under a branch: If UNITID Is Not Empty

You don’t need the If authenticated=1 branch.