ACT NOW: The Alteryx team will be retiring support for Community account recovery and Community email-change requests Early 2026. Make sure to check your account preferences in my.alteryx.com to make sure you have filled out your security questions.
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The thing is, you will need to fill the first text input with valid cliend_id/username/password/client_secret parameters. Your Power BI Service/Azure ADMIN can help you to get this. Once you do it, the first API call will then return a valid access_token.