Authentication (e.g. identifying visitors) is usually done outside of QlikView/QlikView server. In your case it is done by Windows using Active Directory (AD). Create a new user in Active Directory, assign a QlikView license to that user in the QMC and grant document permissions if you are using additional security techniques (like Section Access).
Note that your Qlik license agreement may not allow you to grant access to QlikView documents from outside your company.