If you are trying to use LockDown Browser and get the above error message, it's likely because you're using a computer running Windows 7 or 8. 

Windows 7 and 8 are not compatible operating systems for LockDown Browser. You'll want to locate a computer that is running Windows 10 or 11.

A full list of compatible operating systems can be found here: What are the computer requirements for installations of Respondus LockDown Browser?