Make sure LockDown Browser was installed using the link intended for your institution. If you found the LockDown Browser installation link using a search engine, the version you installed might not connect properly to your school's LMS (Learning Management System).
If you are presented with a list of server names when you start LockDown Browser, such as “Blackboard @ MySchool” and “Moodle @ OtherSchool” make sure you select the correct server (ask your instructor or local support staff if you are not sure).
Make sure that your username and password are valid. You can test this by logging into your course using a typical browser, such as Edge, Firefox, or Google Chrome. If you are not able to log in with a typical browser, contact your institution’s helpdesk for assistance.