Enphase periodically releases new software for the Envoy and the microinverters to enhance performance or to fix bugs. Microinverters updates are packaged with the Envoy software updates and delivered to the Envoy over its Internet connection. The Envoy then updates the microinverter firmware over the powerlines connecting the Envoy to your array.
There is nothing you need to do to receive the updates. If an update is required to fix a bug or improve your experience of your system, Enphase will push that update to the Envoy.
MyEnlighten updates are released on a regular cadence as new features and bug fixes are released. There is nothing you need to do to receive the monitoring updates.