Issues with logging into apps outside of iOS

Here's a quick description that I left on my case:

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I use iCloud to pay for HBO Now. I’m logged in I my phone/iPad, but it won’t let me log in on any other device. I try to login to HBO Now with my iCloud ID (multiple times) and it ultimately tells me it doesn't recognize me as a user of their's. Same issue happens when I try to reset my password on their site.

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There is no way to call HBO for support, so they are non-helpful at this time. Apple was not sure what the problem was and has left the case open for the moment. I am hoping to get this resolved sooner than later as I have family in town for the next day or two and am hoping to show them some shows available on HBO and would rather show them there rather than pay outright.

Dale