Google's John Mueller was asked if using "admin" or "author" for the author name on articles would be okay for some web sites. The answer was not 100% clear, but he suggested for YMYL categories of sites, it's best to stay away from generic author names like that. But even for other sites, it might be best to leave the author name blank as compared to using "admin" as the author name....
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Google: Using Admin Or Author For Author Name On Articles
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