Resolved: UnauthorizedAccessException for write or read file in Xamarin.Forms Android (C# - Xaml)

Introduction:

Android considers accessing external storage to be a dangerous permission, which typically requires the user to grant their permission to access the resource. The user may revoke this permission at any time. This means that a run time permission request should be performed prior to any file access. Apps are automatically granted permissions to read and write their own private files. It is possible for apps to read and write the private files that belong to other apps after being granted permission by the user.