You can follow the steps mentioned below and then try attempting the test.

Step 1: Check if your camera is working properly from any of these websites

https://webcamtests.com/

https://www.onlinemictest.com/webcam-test/

Step 2: Check if your device is connected to only a single camera. Having multiple camera sources can cause an issue. You can disconnect any other camera devices before starting the exam (it is preferable if you have a built-in cam).

Step 3: Check if any Antivirus Software/Extension is blocking the camera access. If yes, disable them.

Note: It is better to use a personal Laptop/PC instead of a company/organization laptop.