I suggest first test the basic guest access using the same captive portal but without sponsor approval and see if it works.
Generally the reason why the user might get redirected back to the captive portal even after successful login is an incorrect redirect ACL.
if you are using ClearPass for authentication and guest access, you should check access tracker which will give you a lot of visibility for guest authentication
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Any opinions expressed here are solely my own and not necessarily that of Hewlett Packard Enterprise or Aruba.
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