No Audio with Zoom via Firefox ESR browser.

Using an old low spec. laptop running 32bit Debian 12 OS; Zoom app. isn't available.  Audio seems to work normally for everything else; with headphones I'd get some broken up audio.  Chat GPT's dubious advice led nowhere except that all fairly obvious steps were taken checked e.g. browser permissions; volume showing Zoom audio running etc.  Bing Co-pilot gave up and suggested trying Zoom.