The microphone needs one setting on this phone.
Chrome only lets pages on your home network use the microphone once you allow it:
1. Open a new tab and go to chrome://flags/#unsafely-treat-insecure-origin-as-secure
2. Type in the box, set it to Enabled, and tap Relaunch.
Until then, the talk button opens your phone's voice recorder instead: record, tap done, and Atlas gets it.