If you are trying to use LockDown Browser for Chromebook with your D2L Brightspace exam, you'll first need to allow pop-ups for your D2L environment in the Chrome Browser.
If you do not do this, you won't be able to move past the "start quiz" page.
To do this, in the Chrome browser, go to "Settings" > "Privacy and Security" > "Site Settings" > "Pop ups and redirects"
Alternatively, you can copy this location into the URL window of your Chrome browser:
Select "site can send pop-ups and redirects".
Then, you also need to click the "add" button under the "Allowed to send pop-ups and use redirects" header, and add your D2L Brightspace URL to the list of sites. The below specification is just an example. Your D2L Brightspace URL will be different.