From your PC's Start menu click Settings, then choose Privacy.
From the Privacy list on the left, under App Permissions choose Camera. Then, turn on Allow Desktop Apps to Access Your Camera. From here you can choose which individual apps to turn on and off. Vast Conference should appear in this list.
Return to the App Permission list and choose Microphone. Turn Allow Desktop Apps to Access Your Microphone to the ON position. Vast Conference should appear in this list.