Launch error : "This interview can only be launched by a logged in agent or employee"

Summary: When we launch an interview from HUB we are getting error message as "This interview can only be launched by a logged in agent or employee. Consult the documentation for more details." I have checked the link Launch an agent or employee interview from a URL (urlisolation.com). We are not using B2C connection, the other option talks about Manage user-based license compliance (urlisolation.com) in which it talks about opauniqueuser.

Has anyone faced this issue? Is it not possible to launch an interview from just url shown in hub? From where can i check this opauniqueuser. Any leads will be helpful.