Desktop: Ensure you have the 'permissions' set at the computer level by navigating to your System Preferences. Here you can locate the Reachify Application to ensure it is 'allowed' to use your computer audio/microphone/etc. You can also find the notification section in System Preferences to ensure Reachify is allowed to send all notifications your way.
Web: You need to ensure whatever browser you are using (Google Chrome, Safari, Etc.) has its permissions set to allow the browser itself to use all features. Once you have done this, you need to ensure the site you are navigating to (xxxx.app.reachify.io) has its site settings set to allow the site itself to use audio/microphone/etc.. You can find this in the system preferences or settings within the browser itself.