Microphone permission prompt not showing up

I am developing on Quest 2.  I am using the Agora RTC SDK which would access the microphone for voice input.  I specified the permission in the AndroidManifest.xml file, and also ask it in the Unity code for access. However, the prompt isn't showing up on Quest 2 like it did on other Android devices.  Is there something missing here? How does the others voice related app do this?