How to enable Respondus LockDown Browser

This is done in Canvas. On the course menu, click on Settings, and then click on the Navigation tab at the top of the course settings page.
Scroll down on the page and locate the list of menu items currently disabled and hidden. On that list, locate “Lockdown Browser” item and either drag and drop onto the list of enabled or visible menu items, or click the three-dot menu and select enable. Scroll down on the page and click save.
Finally, on the course menu, locate the newly added Lockdown Browser menu item and click on it to complete the setup.