Hello Charle,
Thank you for your message.
Such issues might be occurring because
admin$ (admin share) is not allowed on the remote machine or you don't have access to it.
In addition, such issues might also be caused by the fact that the
disc Z is mapped on the Viewer computer and, therefore, is not available and cannot be used by the
Remote Install Tool. In order to avoid this kind of issues please make sure that the Z drive/letter on your Viewer machine is empty and available since Remote Utilities temporarily uses the Z drive for the installation/upgrade process via the Remote Install Tool.
Hope that helps.