You must be on Android. All installs/updates are handled by Android (Google). This is not Quest specific.
Updates are automatic by default but you can initiate an update by starting the Play Store app, accessing the "hamburger" menu on the top left then selecting "My apps & games". It should show you all your pending updates. There you can update The Quest or all your apps. (I recommend updating all, especially the "Google Play Games" app, apart from The Quest of course.)