You will have to provide more details if you want a meaningful answer. Do keep in mind that you are posting on a public forum, so maybe not too much detail, i.e. anonymised where appropriate.
"Logged in with JIRA admin credentials" - logged in into what? What was the URL you were trying to access?Normally you don't "land on Confluence admin page" unless you were trying to access it in the first place.
Usernames and passwords are irrelevant when you get access to particular part of the application. Group membership for the username is relevant so check your groups. Is your "JIRA admin" be a member of confluence admin groups?
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