KardiaMobile functions using an audio mechanism to transfer your EKG signal from Kardia EKG hardware, to the Kardia App on your phone, tablet, or watch. So, access to a microphone is always needed to record EKGs. This allows users to avoid any sort of pairing when setting up their device and helps the battery last years instead of days.
So, when you’re prompted during setup to let Kardia access your microphone, say “yes”.