I have rewritten a sentence as follows, and my cousin asked me why I didn't use any article before administrator/owner/creator/manager.
On the user profile page, I need to add a block showing the groups for which the user is administrator/owner/creator/manager.
I didn't find a satisfactory explanation, and I am wondering if not using the article is correct English.
Is not using the article before administrator/owner/creator/manager correct/acceptable English?
If the sentence is fine without the article, why is it possible to write it without an article?