Following error shown when trying to add my first contribution in Microsoft script center. I am looking to add script to azure automation runbook gallery.
Your post is not a code issue but a resource access issue on a site the Stack Overflow does not control, as per your error message.
You should reach directly to the scriptcener / powershellgallery owners/managers to address why you are having this issue.
There are many blog posts on how to do this type of submissions, generally speaking.