I followed the instructions as you laid out, but it was unable to create additional instances afterward. This was in the console:
Failed to unpack AMP.
 (UnauthorizedAccessException) : Access to the path 'C:\AMPDatastore\Instances' is denied.
at IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) at IO.Directory.InternalCreateDirectory(String fullPath, String path, Object dirSecurityObj, Boolean checkHost) at IO.Directory.InternalCreateDirectoryHelper(String path, Boolean checkHost) at InstanceManagerPlugin.LocalInstanceManager.()
I uninstalled and reinstalled AMP in its entirety and things seem to work now... but this is a problem...
All of this happened again recently after I reinstalled the computer, installed 18.104.22.168, then later upgraded the instances and then manager application to 22.214.171.124... I am concerned that this may happen ever time the applications may need to be upgraded...