Hi. My name is***** you for your question and the opportunity to assist.
Can you tell me what type of update you are trying to download?
Are you using a Mac or Windows computer?
I understand. I'll send your question over to the Mac experts. You'll receive an email notification when one responds. Thank you.
One more question: when you first set up the Mac you should have been asked to create an administrator password.
Have you tried using that to install the update?
Please see this from Apple: https://support.apple.com/en-us/HT201760