“Bridge says it does not have access to my microphone (or camera).”
Here’s the fix:

First, navigate to settings in Google Chrome. Click the three dots in the top right of Chrome:
Google Chrome Settings For Kotter Group Bridge Voip Phone System

Then click on Settings > Site Settings:
Settings In Google Chrome For Voip Phone System Bridge By Kotter Group Privacy Security Settings Google Chrome For Bridge Phone System

Next click on either Camera or Microphone. Then click on the one that says https://my.bridge.insure:443
Bridge Camera And Microphone Settings In Google Chrome Permissions

Verify or change the setting for Camera and Microphone to Allow:
Allow Camera And Microphone For Kotter Bridge Phones In Google Chrome Settings

Once these are both set to allow, your headset should be working correctly in Bridge.

Bonus Tip!
While you’re here, scroll down to notifications and set that to Allow. Then the Windows notification system will alert you to incoming calls and Chat Plus notifications!